Certified Transmission

Once Again, Not the Transmission

2012-02-08T09:10:00.000-06:00

Written by Mike Steen - Technical Director

It’s very easy to get steered in the wrong direction when diagnosing a transmission complaint. There are so many sensors and components that can cause transmission-like symptoms that it’s easy to assume you’ve got transmission problems, no questions asked. From a customer’s perspective, they see what they assume to be a huge repair, and they’re convinced it’s going to cost them an arm and a leg. Of course, when it turns out to be something else, you get the opportunity to be a hero and gain a customer for life.

A couple of years ago, I recall reading an article by Wayne Colonna that pointed out several external factors that can produce transmission-like symptoms. Here, I’d like to point out another unlikely component that can send you into a diagnostic tailspin: the alternator.

A very common complaint among Dodge diesel truck owners is of a cycling torque converter lock-up and/or 4th gear hunting with no codes. These very well may be caused by a bad alternator diode. While in cruise, a defective diode can allow high voltage spikes, causing electrical noise within the TPS circuit. Also, you’ll find that Dodge ran the TPS wiring harness alongside the alternator’s wiring harness, which can create electrical noise in the TPS circuit. Also, besides the obvious havoc that a poor charging system, bad diodes and bad grounds can have on a vehicles electrical system, you also face the issue of mechanical failure.

Here’s something I wasn’t aware of until recently; there’s a trend with several vehicle manufactures where they’re using what’s called an Isolator Decoupler Pulley (IDP). The IDP is an improvement on the overrunning alternator pulley, which has been around since 1990. Basically, an IDP is an alternator pulley that works in the normal way, except it has a one-way clutch that allows the drive belt to freewheel under certain conditions (like sudden engine decelerations). Incorporating an overrunning alternator pulley or an IDP eliminates belt noise under the hood. It also requires less belt tension then the previous systems. Less tension means fewer loads and less fuel used.

One of the most common problems with these systems on higher mileage vehicles is bearing noise. A worn bearing can cause a brief noise when you shut the engine off or during the 1-2 shifts. This complaint is more likely to come from a driver with a heavy foot that makes a lot of wide open throttle upshifts. One thing to keep in mind is the engine decelerates rapidly during hard shifts. If you suspect a bad bearing, have someone rev the engine and quickly shut the ignition off and listen for a noise at the front of the alternator.

Diagnosing these would-be transmission problems can be a challenge, but also rewarding. It’s one of the best ways I know to get a customer telling everyone they know how great your shop is!

All Plugged Up

2012-01-16T16:29:00.003-06:00

Written by Jody Carnahan and Dave Wilkes of Wilkes Transmission

We recently attended the EXPO in Vegas and like all others, you always meet up with other ATRA members wanting to talk shop. On this occasion I had the pleasure of meeting Dave Wilkes of Dave Wilkes Transmissions. We started talking shop (when we were actually supposed to be relaxing at the cocktail reception) but you know that’s never going to happen when one you bring up a problem with a vehicle that they recently had in the shop and like all technicians, I wanted to listen.

In this particular situation, Dave was working on a 2001 BMW 740i with a 5HP24 transmission. The vehicle originally came in with a complaint of leaking out of the front. The unit was very low on fluid, was slipping and the fluid was burnt. They recommended that the transmission be overhauled because of the above conditions and the mileage on the unit. Everything went normal with the rebuild and the customer left with a good working unit.

Three months and 4,000 miles later, the customer returned with the vehicle. The complaint was that under stop and go conditions the transmission would sometimes clunk and would downshift on its own for no apparent reason. After driving for 20-30 minutes, under the same stop and go conditions, the transmission would start shifting late through the gears. There was also oil on the back of the vehicle and it was smoking. On the initial inspection and road test the transmission appeared to perform normally, but he did notice the fluid level was about a quart low. When scanned, he found it had codes 049 (symptom gear check) and 034 (transmission sump oil temp high).

The codes were cleared and the vehicle was road tested again. The transmission would operate normally with the fluid temp around 100 degrees C (212 F), but the 049 gear check code would return and it would also go into failsafe. Knowing that the vehicle owner typically drove in stop and go traffic, it was decided that he needed to drive the vehicle under the same conditions.

After driving the vehicle under these conditions, the transmission temp reached 130 degrees C (269 F) and the computer appeared to put the transmission into a high temp shift mode strategy. The transmission would take off in 1st; have a late shift command to 2nd and a late shift command into 3rd. Once the transmission fluid temp cooled back down to 120 degrees C (248 F) it would operate normally. It also operated normally while driving on highway at steady speeds with a fluid temp of around 100 degrees C (212 F). One other note: The converter clutch engagement appeared to function normally regardless of the driving conditions.

With the vehicle back at the shop, an inspection on the rack revealed the transmission leaking from the front pump area. This would require the unit to be removed from the vehicle.
When the transmission and torque converter were inspected, there were no internal problems found. The valve body and solenoids were replaced based upon the 049 code.

With the transmission installed back into the vehicle, it was time for another road test. The transmission operated normally and no codes returned. It was now time to do some more stop and go driving.

After doing 20 to 25 take off and stops, the trans temp went from 100 C (212 F) up to 130 C (269 F), and you guessed it, back to the same high temp shift strategy. It was time to dig a little deeper.

When the transmission was removed, a thorough flushing of the cooler system was performed. The system in this car is very unique. It incorporates a transmission fluid heat exchanger (cooled by the radiator) through a series of hoses and a thermo check valve.

Here is a brief overview on how the system works. The radiator has two sections and is a cross-flow design. The upper 4/5th section are used for hot engine coolant and the lower 1/5th is a low temperature residual coolant storage area. This is used to cool the heat exchanger. (See figure below). The system also uses an integral thermostatically controlled valve that sits on top of the heat exchanger. When the transmission fluid is cold, coolant is guided from the engine (water cooled housing) to the heat exchanger. This part of the system is actually used to warm the transmission fluid through the heat exchanger. As the transmission fluid rises to operating temperature the engine coolant temperature also rises. This causes the wax core in the integral thermo controlled valve to expand. The expansion pushes on the regulation valve and closes the warm coolant port while it opens the low temperature coolant port from the residual 1/5th storage area of the radiator. Thus the 1/5th section of the radiator sends coolant to the heat exchanger for cooling.

Now that we had a little better understanding of how the cooling system works, it was time to figure out why the transmission was getting this hot.

As stated previously, the transmission performed well and had good torque converter clutch application. We did not suspect it was causing the overheat condition. A cooler flow check was performed and it was flowing 4 quarts in 20 seconds. It was decided that the most probable cause would be the heat exchanger and or the thermo valve.

With the new heat exchanger and thermo valve installed, it was time for another road test and to our surprise this made no difference in the transmission operating temp. The new exchanger had a cooler flow rate of 2 quarts in 20 seconds which was more than adequate cooler flow. Now what?

There was only one component left in the system that could be the culprit. A new radiator was ordered. After replacing the radiator, there was a significant difference in the overall operating temp. Under normal driving conditions the trans temp was around 90 degrees C (194 F) and under repeated stop and go conditions the temp never got over 106 degrees C (223 F).

We now had a successful repair. But why was the radiator causing the problem? As stated previously, it is the lower 1/5th of the radiator that is used to cool the heat exchanger. When the tank was removed from the old radiator the lower 1/5th was plugged with debris. When the coolant was diverted from the 4/5th section to the lower 1/5th low coolant temp section there was not adequate coolant getting to the heat exchanger.

Understanding the AW 55- 50 Neutral Control

2011-12-07T16:43:00.002-06:00

Written by Jerry Huerter - Diagnostician at Overland Park, KS

We recently had a 2001 Volvo S60 come into or shop with a smoked AW 55-50 transmission that needed to be replaced.

The AW 55-50 transmission has a feature that Volvo calls “Neutral Control”. What it “Neutral Control” and what is its function? To tell you the truth, I wasn’t really sure, but below is what I was able to both find and figure out about it.

When coming to a complete stop in drive with your foot on the brake, the TCM waits 2 seconds before disengaging drive or shifting the transmission into neutral. This feature is designed to reduce emissions and to minimize any idle vibrations. When the brake pedal is released, this re-engages drive. This is a very smooth and seamless process that is never felt by the operator.

However, when replacing the transmission special attention and very specific directions must be followed to adapt the new unit to the car. If adaptation is not properly completed, then a very noticeable "thud" will be felt shortly after coming to a complete stop. When the brake pedal is released, a harsh engagement will also be present.

Volvo has published a TSB (TSB 43-38) that requires the use of their VADIS to put the car into Adaption Mode. Once this is hooked into the system, you can begin the adaptive learn and test drive.

After the transmission is in adaptive mode, the orange triangle in the center of the instrument cluster will flash just after a perfect shift is obtained. Volvo considers a perfect shift as one where the TCM has reached its adaption target for that particular shift. While in Adaptive Mode, you will experience all of the types of shifts listed in the TSB until the light flashes to tell you it was a perfect shift. When all the shifts are perfect you are done, the adaption is complete.

Does this sound like this might take awhile? Yes it does!

I understand that the last Snap-On scan tool update (11.2) included the updated software for the Volvo. Does anyone out there have the 11.2 update and can you tell us if it has the Volvo Adaptation Mode or do we need to take this one to a Volvo Dealer to have them do the Adaption relearn?

Sometimes Lucky is Better than Good

2011-11-03T09:14:00.000-05:00

Written by Dana Deeke - Diagnostician at Lincoln NE

I had a mid-90’s Dodge Caravan come into the shop with the complaint of a rough noise/feel when driving above 45-50 miles per hour. The van had been into a couple of other local shops to try to find the noise with no success and the customer was getting frustrated.

As normal, I started with a road test to see if I could duplicate the Customer complaint. Sure enough, upon reaching 45 miles per hour the van started to make a low, growling sound and you could feel a little vibration thru the steering wheel. It was time to get the van inside and do a visual inspection.

I started by inspecting the transmission and engine mounts to see if they were cracked, broken or sagging. Though the mounts did not look like new, none were broken and I did not see anything that looked like it would cause the noise or the vibration that I was experiencing. I decided to take one of our R&R techs along for another road test to see if he could confirm what I was hearing and to help me pinpoint the noise.

Once again the noise started at about 45 miles per hour. The tech that I had riding with me indicated that the noise did not seem to be coming from the passenger side of the van. Like me, he could not narrow it down to a probable location. I did find that changing the load on the front end by swerving slightly back and forth had no affect on the noise. However, I did notice that once the noise started, the intensity of it did not change with increased speed but that when the speed was reduced below 45 mph it would gradually fade until you could not hear it at all. What next?

I brought the van back inside and put it up on the lift at let is run while listening underneath for any unusual noises. I ran the van up to 45 mph and no noise. This was getting interesting. I had a loud noise that needed road speed to make it occur, but more road speed did not make it worse and it would not make the noise with just the drive train moving. The vehicle itself had to be moving.

This is when I started to look at things a little differently. Was it possible that air moving over the vehicle was somehow creating the noise? I started to look at items like the trim around the windows, the wiper blades and other non-drive parts.

You may be a top rated technician, but now is where it is sometimes better to be lucky rather than good.

It was cool when the vehicle came in, so the air conditioning had not yet been turned on. It was starting to get warm while I was sitting there in the shop so I turned on the air conditioning. All of a sudden there was a loud bearing type noise that was coming from the cooling fan. The sound did not match what I was hearing on the road, but it did pique my curiosity.

I wondered if this was the culprit, maybe it just sounded different out on the road. I pulled the fan relay to prevent it from engaging and started out on another road test.

Much to my disappointment it still made the noise. What the heck? I went back under the hood and turned the fan by hand, it was really rough feeling, and that is when it hit me. Maybe the fan running at full speed didn’t make the same sound but what about when the fan was not engaged, but air entering the grill going down the highway would turn the fan at a much slower rate?

It was time for one more road test. I left the fan relay out, but this time I put a wire tie around the fan so it could not turn at all. Bingo, no noise! The air moving through the grill was turning the fan slowly and the bad bearing was the cause.

This explained why the car had to be going down the road to make the noise and why changing the load on the front end by swerving would not change it, as well as why it would taper down and quit all together when the road speed dropped.

It was a stroke of luck that I turned the air conditioner on. Otherwise I am not too sure I would have looked at the fan causing this problem.

So sometimes it truly is better to be lucky than good.

Hot Off the Wire

2011-10-24T11:08:00.000-05:00

Written by Dave Finley - Diagnostician at Bellevue NE

My first appointment of the day was a customer with a 2001 PT Cruiser. Their complaint was, “It feels like all the gears are slipping, and a light is on in the gauge panel.”

I started my evaluation with a fluid check and pulled the codes. The fluid level was normal, and the code I got back was a P0750 - solenoid error in the TCM. There were no ECM codes.

After clearing the code I started my test drive. The transmission preformed well, but I did experience what felt like a slight engine stumble when going up hills. It was intermittent, but it did occur twice during the drive. The check engine light also came back on.

I suggested that the customer allow us to conduct a Level One diagnostic evaluation and he gave me the ok, so I attached the scan tool and checked for additional codes. The only set code was the P070 for the TCM; again, no engine related codes.

I decided that my next step would be to do an ohm test of the four solenoids at the TCM connector. The 2001 PT has the TCM mounted inside the left fender well, which requires you to lift the vehicle and remove the tire and fender panels to access it. Thankfully, this also allows you to see the front of the transmission and check it for any leaks.

There was definitely a leak somewhere in this unit. It was covered in used ATF. On closer inspection, it appeared to have a solenoid pack leaking (among other possibilities).

The ohm test of all four solenoids was 1.7, which is well within the specification. At this point, I started to wonder if the L-R solenoid could be a heat-related issue. It very well could be causing the unit to go into limp mode (2nd gear) and maybe that was what the customer was feeling when “it felt like all of the gears are slipping”?

While I was doing the tests, the customer decided that due to the age and mileage on the transmission, he wanted us to stop our testing because he might want to just replace the whole transmission.

I stopped the troubleshooting process and assumed that either the customer would be back for a replacement unit, or would be back to allow us to determine the cause of the problem.

A few weeks later, the customer did return to our shop with a complaint of a 1-2 shudder. The check engine light was back on with the same P0750 code. There was also someone else’s replacement transmission installed in the PT.

I continued with the tests that I had started weeks before but had never got to finish. I disconnected the TCM and solenoid pack so I could test the L-R wire from pin 7 to pin 20 at the TCM. It tested good for continuity, but I decided to apply 12 volts to the wire just to make sure that there was no voltage drop. The wire was fine, with no drop I re-checked all of the connections and tightened the ones that were loose.

I reassembled everything and took the PT out for another road test. Everything was looking good until the temperature reached normal operating level. The PT began what is best described as a shuttle shift from 1 to 2, 1 to 2, and 1 to 2. The check engine light did not come on though.

It felt like engine stumble or maybe ignition fallout, but was now worse than it was during my initial test drive. Was this engine related, or something else? It felt like a shuttle shift, but he more I drove it, the worse it became. It almost felt like it was going into lock up after 2nd gear, and then dropping back out. Lock up; lock out, over and over again. The check engine light finally came back on and the same P0750 code was back.

I decided that it had to be the wire from the L-R solenoid even though it tested good. I replaced the wire from pin 7 to pin 20. With the new wire in place, I went for another drive. Everything worked perfectly. The customer left happy and so was I. I started trying to figure out how this could have caused the problem.

There must have been an intermittent short in the wire that only occurred when the PT was up to operating temperature. The tests I did on the wire were while it was cold. The wire passes through some very tight places to get from the engine compartment to the fender well and it can get very hot in there. The L-R solenoid does become the TCC solenoid after the switch valve moves in the valve body and commands the shuttle during the 1-2 shifts.

Simple Wire Problems

2011-10-14T15:10:00.002-05:00

Written by Chris Foster - Topeka Store Manager

A few weeks back, we had a customer come to the shop and say “Hi! I was sent here by so-and-so, and he said you would be able to fix my car, because he does not have time to figure it out”. “Well I am always up for a challenge, what is going on with it?” We then got into a discussion of how long he has been working on the car, and how everything "works great”. She then explained to me that the dealer looked at it and said it was going to be $XXX to fix it, and she just didn’t think they were right because “everything works ok… It is just the ALL WHEEL DRIVE DISABLED light is on, and nobody can find out what is wrong with it”. “Sure” I said, “leave it with me and I’ll see what I can do.”

Wow, was I in for a treat. I brought the Buick into the shop later that day to perform the preliminary checks and noticed the information center flashed AWD DISABLED, and the message remained on throughout the entire diagnostic and road test. I instantly agreed with the customer that this was “bothersome” to say the least, not really even caring if the all wheel drive worked. Just this annoying message on the instrument panel was enough to make a person not want to drive the car.

I hooked up my scanner only to reveal that there were no codes present in any of the modules. “This is crazy,” I thought to myself. “How can there be a warning message displayed with absolutely no diagnostic trouble codes? And where am I going to go from here? It has to be a bad scanner!” So I went through the pain of borrowing a scanner from a friend of mine at the local dealer to be able to read all of the ABS data and find out why the AWD DISABLED message was displayed. We all know the sad outcome of that tale! Nothing. No code in the PCM, BCM, ABS, IPC or any other module. Boy was I stuck.

I did some quick research on the internet, and all that led me to was a whole bunch of forums with people asking how to turn off the AWD DISABLED message in their 2000-whatever vehicle. I read through them as time permitted, and needless to say, I did not find much help. I called some buddies at the dealerships and I got all kinds of answers, from “you have to replace the rear differential” to “replace the pump check valve” (whatever that is) to “try and reprogram it”. All good information, but, just not really giving me anything solid to go on. I completed my internet research and came up with the ever popular “tire size variation” starting point.

Well, sure enough, just before this all happened, the owner purchased two new rear tires, and was saving up for the front ones. The place that the tires were purchased at told her the front tires were fine, and she only needed rear ones. The tread depth was close, but had a significant difference. I consulted the owners manual (of all things) and there was a description of her concern in the ‘warning lamps’ section. It read “the AWD DISABLED message will be displayed in the event a temporary spare is placed on the vehicle.” It then went on about the criteria for this event and stated “the message will go away once the tire variation was corrected.”

“Perfect,” I said. “Now I have documented proof to show the customer.” She said she would have to save up for the tires, and if that didn’t fix it… she would be back to see me.

As luck would have it, it only took her one week to get the new tires and to put 150 miles on the SUV. I only know this because that was the only thing different about the vehicle when it came back with the same annoying message displayed on the dash. “Oh well, I needed new tires anyway” is how we began that conversation. “That had to be done anyway… leave the rest to me” was my reply.

I put all other advice and thoughts of an "induced" problem aside and pulled up a wire diagram. “WOW! This looks difficult,” I thought to myself. A power wire, a signal wire, and a ground, one fuse, a check valve, and a PCM make the whole program work. Way more simplified than trying to find out why shift solenoid ‘E’ in a 5R110W loses voltage when you select D3… or is it?

A week later, I had a Chevrolet Venture van come in with the same problem. I used it to write this article and take photographs as the repairs were made. Although the Buick beat me up a little bit, this one was “quick and painless” (we all know what that means).

I checked the fuse to make sure there is power on both sides, eliminating the ignition switch as the source of the problem. The simplified wire diagram didn’t really show any types of splices or connectors that concerned me, and so I decided to check the entire wire, from the source to the component. Since here was 11.4 volts at the check valve in the rear differential and 0.01 ohms resistance from the fuse panel, I knew it was not a voltage problem. I then unplugged the PCM and found the LT BLU signal wire in pin 74. There was 0.42 ohms resistance in the wire from the PCM to the check valve, which should be ok.

That left me with the ground wire. It had 5.71 ohms resistance, which of course we need to be as close to 0.00 ohms as possible. A quick check of the simplified wire diagram shows the wire grounded on the B pillar. Easy enough, must be a “pass through” connector, maybe under the seat or in the fire wall. There is actually three connectors on a “pass through” bulkhead connector right behind the drivers seat- not shown in any diagram, exposed to water, salt and the elements, including the ever popular drive-through car wash that sprays the undercarriage.

Not being able to find a connector end, I replaced three of the female terminals, soldered the connections and applied a little dielectric grease around each plug to help prevent the problem from re-occurring. I’m happy to report that the AWD DISABLED light is off, AWD works, and the customer is happy.

The all-wheel drive Chevrolet Venture van came into the shop with the AWD DISABLED message displayed on the information center

The first thing I did was check to make sure there is power on both sides of the fuse, in order to eliminate a problem with the voltage source

The connector at the check valve shows it is a simple three wire system: Power, Ground and Signal

Checking the wires from the source to destination eliminates the need to make test points throughout the wire harness

It was pretty easy to locate the light blue wire at the PCM connector

The power wire had 11.4 volts on it, and had the same resistance as the light blue signal wire

There was more than usual resistance for the ground wire, just checking it at the frame, but also at the negative battery post

There is a pass-through connector just behind the driver's seat, not illustrated in the simple wire diagram

Once unplugged, I could see where the corrosion begins

The ground wire at the check valve was not much better

After replacing the three female terminals, and cleaning the male terminal, I applied dielectric grease to the connectors to hopefully keep this from happening again

All is good now

Chrysler Transmission Range Sensor

2011-08-01T13:12:00.003-05:00

Written by Mike Steen - Technical Director

The Transmission Range Sensor (TRS) has 3 primary functions:

1. Provide a PARK/NEUTRAL start signal to the engine controller and the starter relay.

2. Turn the Back-up lamps on when the transmission is in REVERSE and the engine (ignition) is on.

3. Provide a transmission range signal to the instrument cluster.

This relatively simple sensor has caused us problems over the years.

In one case, right after a fresh install at our Lincoln store, they had an alarming problem. With the vehicle running and in the park position, if you took your foot off of the brake, or opened the door to get out, the horn would start honking and the headlights would start flashing.

They also noticed that the indicator lights weren’t functioning correctly. When they put the vehicle into park position the “P” on the indicator would not light up. This condition was not there with the original unit.

They pulled the pan and found that the Neutral Switch pin that rides on the rooster comb was not contacting the comb when in the park position. This was a late model unit and used the range sensor style switch.

The issue was that the bracket between the case and the adapter had two washers installed between the adapter and the case. This moved the sensor too far from the rooster comb.

The computer could not sense that the vehicle was in park and triggered the out of park alarm.

Proper installation is: one washer on both sides of the bracket (see figure 1). This unit had three washer with two installed between the bracket and case. Removing one of the washers next to the case corrected the problem. You also should be careful when replacing the TRS mounting (see figure 2) bracket.

Any damage or miss assembly of the bracket can also cause the TRS to give a faulty reading.

The linear motion of the TRS is so short that a few thousands of an inch is enough to cause the TRS to not read properly.

When installing the TRS mounting bracket, torque the bracket to 25 feet lbs. using the Chrysler adapter # 8581 or equivalent.

The two screws that hold the TRS to the bracket torque is 30 in. lbs.

Another complaint we’ve seen with this set-up is no Park or you are unable to move the shifter linkage all the way into the Park position.

If you have this complaint, first check to determine if you have the late style TRS.

If it is correct, try removing the switch. If you’re now able to get Park, there’s a good chance the Neutral Safety Back-Up Insulator (see figure 3) is worn.

Figure 3

The new style TRS applies more pressure to the plastic insulator then the previous Neutral Safety Back-Up switch and can wear to the point that the linkage can’t get past one of the contacts.

To repair the problem the valve body will need to be removed and the insulator replaced.

Cooler By-Pass

2011-07-01T13:10:00.015-05:00

Written by Mike Steen - Technical Director

External cooler by-pass valves are becoming more and more popular it seems. There are also many different variations of these by-pass valves. It’s important that you check the cooler lines and cooler closely to see if the vehicle your working on has one of these by-pass valves. In most cases they can be removed and cleaned.

Most all automatic transmissions incorporate some sort of by-pass in case the cooler becomes restricted, but they are typically found inside the unit.

One example of an external by-pass would be on a 4R100 Fig 1. This is a mechanical by-pass that is located in the tube that bolts to the case. Another example would be a thermal mechanical by-pass, like the one shown in Fig 2 or like the one Fig 3. In the case of the 4R100 it’s not a problem when it comes to flushing the cooler lines and cooler, because it bolts to the transmission and is separate from the lines. Where it does become more of a challenge is when the by-pass is in the cooler or lines, like the one in Fig 2 and 3.

In either case if the thermal by pass valve is not heated when flushing, to fully stop by-passing the cooler, you will get little if any flushing of the cooler.

Here’s another thing to consider. If the cooler is plugged and there is a mechanical or thermal mechanical by-pass in the lines you’re flushing, it will by-pass the cooler. In which case there would still be flow, but would not have sufficient cooling. If your cooler flusher has a pressure gauge, it should indicate higher then normal cooler pressure if the cooler is restricted.

The best way to insure a proper flush is to flush around the by-pass if possible. Or you might have to get creative, and make a plug like the one pictured Fig 4 that you can install in place of the by-pass valve. That way you guaranty you’re flushing the cooler.

This chart shows the flow rate at different temperatures of the thermal mechanical by-pass pictured above.

Verify the Systems Before Condemning the Transmission

2011-06-01T13:50:00.007-05:00

Written by Randy Peterson - Diagnostician

A few months ago a customer brought in a 2003 Dodge 1500 Pickup with a 5.7 Hemi and 545RFE transmission. The check Engine lamp was on and the truck would not accelerate from a stop unless you put the transmission in second gear. I started the preliminary check procedure by checking the fluid. It was full, not in great shape but no burnt odor. Next, I scanned for diagnostic trouble codes. The ECM stored a couple EVAP codes and the TCM had a P2706 – MS (multi-select) Solenoid Circuit. Oddly enough it did not have a P0700 (Trans Control System Malfunction) stored in the ECM. This vehicle utilizes an ECM and separate TCM. After a short road test the customer’s concerns were confirmed. I cleared the DTC and road tested it again to see if the code reset and it did. Further diagnostics were required. The vehicle owner authorized the diagnostics, and we began the process.

The first test I performed was on the electrical systems. This included testing the battery and verifying that the starting system and the charging system were operating correctly. Free State fully charged battery voltage should be around 12.6v. 12.4v is already considered 25% discharged. Cranking voltage should never drop below 9.6v and good running voltage usually ranges around 14v. It amazes me how many times this step is over looked in the diagnostic procedure. Low voltage, poor grounds, faulty alternators can wreak havoc on electrical components. You want to be sure if you find problem electrical components, a bad battery or faulty alternator does not cause the new replacement components to fail again. Thanks to Vince Fischelli for teaching me that.

Next, I printed off a wiring diagram and the published diagnostic procedure. I studied the diagram, gathered solenoid specifications and determined my next point of attack.
The TCM is the 60-pin type, similar to the ones used on the 604’s and 42LE’s. I located the TCM and harness, identified the pin(s) I wanted to check and started with (Multi-Select Solenoid Control) pin 40. I performed a simple Ohms test to see if there was an open from the TCM to the solenoid. There was no open. I needed to verify my findings so I tested all the solenoids. They all tested the same. We all know that an Ohms test is no indication of a good working system, so I load tested the solenoids and measured the amperage while activated. This tells me if the solenoid is working and if it continues to work once it gets hot. I was not able to use bi-directional functions because the TCM would go into fail-safe and shut the relay off. With the TCM disconnected I ran fused power to the connector. With this system, the solenoids are grounded and the TCM supplies power. I was able to determine that from the wire diagram. I powered pins: 19, 20, 40, 55, 59, and 60. All of the solenoids were 6.5 amps, including the MS solenoid. That is within the normal operating range. I ran the test again with the same results. My conclusion was a faulty TCM. I reconnected the TCM and road tested the unit. The code returned and it went to Limp Mode.

We recommended a TCM replacement and an ECM re-flash. The owner declined and took the vehicle. Who knew testing all of the solenoids at this time would pay off at a later date? The story does not end here.

The owner took the vehicle to the local Dodge dealer for their opinion. I can understand a second opinion when there is a large cost involved. The dealer advised that the solenoid was bad and needed to be replaced. This repair was about half the amount we had estimated, but remember they were doing something completely different than what we recommended. The owner liked their price and authorized the repairs. Needless to say, it did not fix the problem. The dealer then told them “it must have a bad transmission then”. The owner left the dealer $450 poorer and the vehicle was still doing the same thing.

The owner heeded the advice of the dealer, bought a carry-out transmission from our company, and installed it himself. Shortly after the installation we received a call stating our transmission does not work and we need to fix it. The vehicle was brought in and I scanned it for trouble codes. A few months had passed since the vehicle was last here and I did not recognize it at first. It had a DTC P2706 stored just as before. Again, there was no P0700 stored in the ECM. Just to be sure, I ran the diagnostic test again. My conclusion was the same, a faulty TCM.

The owner purchased a TCM from the dealer that recommended the transmission exchange. I’m not sure how that discussion went, but he proceeded to install it in our parking lot after hours. The next morning I was to check the installation and perform any pre-road test functions. I started my road test satisfied the vehicle would be fixed. When I started to take off, the Check Engine lamp came on and it was again in Limp Mode. I was shocked to say the least. What happened? I checked the codes, no P2706. This time P0750: L/R Solenoid Circuit Error and still no P0700 stored in the ECM. I knew from my previous test all of the solenoids were good. I was so familiar with the test I did it again. I concluded that the solenoids were good. The replacement TCM must be bad. I called the dealer and they supplied the owner with a warranty replacement. The owner installed the TCM. I performed the pre-road test functions and drove the vehicle. Yahtzee! It works, and it worked great.

I felt very comfortable that my diagnostic procedure was correct. It verified all of the working circuits under load. It also verified the support systems; battery and charging system were in good working condition and not contributing to the failure. I tested ALL of the solenoids, not just the one in question. That would help me later on when faults kept reoccurring and it provided a good comparison of the solenoids.

Why are parts replaced without proper diagnosis?

Is there a lack of knowledge or carelessness?

Do technicians not understand the circuits and how they work?

There are outstanding training programs out there but you have to take the classes and then practice what you have learned.

We charge for diagnostic time. It’s an important process for your companies’ creditability and it doesn’t waste the customer’s money with unnecessary parts replacement.

Solenoid Operating Pressures

2011-05-01T11:57:00.001-05:00

Written by Jim Richardson - Technical Director

With the quantity and price of solenoids becoming a substantial additional investment in the price of a transmission reman, testing and reclaiming the solenoids has become mandatory.

Every once in a while you run across a scenario that has you scratching your head. This was one of those units.

Our warranty dept. received a call from one of our retail locations. They had a 2002 Volkswagen Jetta with the O9A transaxle. The unit had been out approximately 300 miles and came back because of a no reverse complaint. All the external checks that could potentially inhibit reverse were investigated, everything was working properly. It was determined the unit would have to come out for further evaluation.

We received the unit back at the plant, and ran the unit on the dyno. Sure enough, when reverse was selected you could feel a partial engagement then a neutral. The drive engagement was fine. After air checking the unit I started with the valve body, taking it apart. Everything looked good, all the valves were free, the casting surfaces, separator plate and gaskets all looked good. No problem found.

I had all the solenoids retested and they checked out fine.

Ok, it’s time to go into the unit, checking all components on the way out. Nothing was stripped or broken and the unit was assembled correctly. The unit was reassembled and it was run on the dyno, still no reverse engagement and no low/reverse clutch pressure. Something is inhibiting reverse, somehow, somewhere.

Forget about looking at an oil schematic, Volkswagen does not publish them. We pulled the unit off of the dyno removed and retested all the solenoids again, they retested good. I replaced the full set of solenoids, as a starting point and put the unit back on the dyno. The unit had a good reverse now. The issue was resolved, now its time to figure out why.

Figure 1

With all the solenoids in hand, it was off to the solenoid dept. All the solenoids were retested and all passed again. We lowered our control pressure on the solenoid dyno from our standard 80psi to 50psi and all passed except one solenoid, the low clutch timing solenoid stuck on.

We increased the control pressure to 75psi and it would work properly. Now its time to duplicate the actual operating pressure of the solenoid in the vehicle. To do this we had to do some creative engineering. Our machine shop fabricated a “test” solenoid with a pressure port. Figure 2.We installed the test solenoid in the unit. Figure 3. The pan was then installed. Figure 4.Then the vehicle was started and the actual solenoid operating pressure was approximately 66psi. Figure 5. It was amazing that only a 9psi difference of control pressure would influence whether the solenoid worked properly or failed (stuck). Now that we determined when the solenoid would fail we had to find out what was going on inside the solenoid.

The solenoid was disassembled and inspected (Figure 6) there was nothing obvious with the pintle or solenoid body, after studying the pieces to see how the solenoid operated mechanically I noticed the small plastic snout of the pintle would seal in the corresponding pocket in the plastic snout of the solenoid to shut the flow of oil off. What was happening was the tip of the pintle would wear enough (not much) and was sticking in the sealing pocket of the solenoid snout. Figures 7 and 8.

Now we know when and how the solenoid was failing. It’s time to see why the unit had no reverse because of the issue. This is a normally “off” solenoid, so oil is flowing through the solenoid and exhausting out the back. Figure 9 shows the circuit working properly. Now enter the solenoid with the sticking pintle. With the solenoid mechanically stuck “on”, the circuit became live. This caused the reverse inhibit valve to stroke. With this valve is in the stroked position the feed oil to the Low/Reverse Brake is cut off causing a “no reverse” or inhibited reverse. Figure 10.

I was amazed at how little a difference on operating pressure made such a huge difference on the solenoid operation. After working with the other solenoids in this unit we are finding the 09A solenoids are prone to be the “sticky solenoid” and we are very picky about reclaiming these solenoids. I want to give a ‘Thank You” to Jim Dial for providing the schematics on the reverse circuit for this unit. It makes understanding what is going on that much easier.

Manual Transmission Fails due to Hydraulic Error

2011-04-01T11:05:00.012-05:00

Written by Steve Logeman, Technical Director

Huh? NV4500 manual transmission fails in the field because of a hydraulic issue? You’re probably saying to yourself “This guys wacked or drinking his lunch if you know what I mean.” There’s nothing hydraulic about a NV4500 5spd manual transmission.

This all starts with a 2002 GMC 2500 with a complaint of sticks in fifth gear. Customer states that this has happened to him half a dozen times since the transmission was installed 2000 miles ago and to make matters worse the technician at our shop couldnot duplicate the complaint.

This struck me as very odd complaint for this type of transmission. Over the years there has been a lot issues with fifth gear and the nut that retains it on the shaft but I do not recall that it ever made the transmission stuck in fifth. No fifth, pops out fifth, hard to engage reverse; these are typical complaints of this unit.

Another big complaint of these units is leaks due to cracked cases, extension housings and 4 x 4 adapter housings.

Needless to say after removing the transmission and disassembling fifth and reverse assembly and the shifter tower inspecting them very closely with a fine tooth comb, everything looks really good. At that point I chose to replace fifth gear and the synchronizer assembly. I did a little dance over it, got out the holy water, knocked on wood and crossed my fingers.

I put it back into the truck drove it several miles with no problems and returned it back to the customer. After all, this unit was shifted in and out fifth a hundred times or so on the bench before and after assembly with no problem. It didn’t fix it but I did get a better description of the complaint this time.

Customer said: “After driving in fifth for more than a mile, the transmission is hard to shift out fifth gear”. Now what? To compound the problem, this unit was what we call a stock unit. A transmission we had on the shelf already built. We didn’t know What was wrong with the original unit before it was remanufactured and shelved?

The only real history I have on the unit is a list of the parts we put in it originally and I saw nothing unusual there.

So in desperation I took one more look at the list of parts put in this unit and the only thing that I have not looked at that might play into this is that the case was changed.

At this point, I locate a core unit of the same type and disassemble both units side by side for comparison. It didn’t take long before I realized that the two units were different and why they were different.

The fifth and reverse shift rails in the case were different. The rail that goes in first (towards the front of the transmission) in the unit in question was completely round (see figure 1) and the one out of the core (see figure 2) had a flat spot machined down the side. The case had a blind hole (see figure 3), so when the unit was full of fluid in the vehicle driving in fifth gear for a long period of time oil would slosh up around the shift rail and hole. It then would eventually fill that void between the case and rail so when you went to remove the shifter from fifth it would hydraulic lock in the case.

You would have pull on the shifter and bleed that oil back threw the clearance between the case and rail. Needless to say, now I know what that flat relief is for in the other rail and why you can shift it flawlessly with no fluid in it. Turns out some cases (see figure 4) earlier ones are open and the round pin works just fine. Don’t make the mistake of installing the round pin into a blind hole case or it is possible to have a hydraulic failure of a manual transmission.

Why Resistance Checks Don’t Always Work

2011-02-26T12:12:00.025-06:00

Written by Chris Adams, Diagnostician

I think I can safely say that we have all been here before: “I ohm-checked the entire circuit and it checks OK.” This article started as a problem found on a particular vehicle, and then it morphed into an article on - in my opinion - a better, faster, more efficient way of checking electrical circuits on a vehicle. In this example I want to show how amperage-based testing on a live circuit can save you time and headaches versus traditional resistance testing on a dormant circuit.

The example used here is a 1998 Oldsmobile Intrigue 3.8L with a 4T65-E transaxle that has a P0753 electrical code - 1-2 shift solenoid circuit - stored in the PCM; no other DTCs are present. The code will not set until the 1-2 solenoid is commanded to turn on. Now we have all seen the diagnostic flow chart for this code. No matter which repair-service publication you use they are all basically the same: Check resistance from here to here and here to here from there to there and from here to ground, bah blah blah; I think you know what I mean. Then we print off a wiring diagram so we know what to look at.

Figure 1

On this vehicle, when you would check resistance of the entire circuit from the PCM to the #26 10 amp trans fuse that sends power to the transmission, you will see that it checks 24 ohms (Figure 1).

After going through the entire flow chart for this code it reveals absolutely no problems, and you get to the end, and what does the chart tell you to do? Yep, you got it: REPLACE PCM. So you scratch your head and think: “What if I spend $400-$800 on a PCM and it doesn’t fix the car? Who is going to pay for it, the customer, or the shop owner? So how can I make sure I am going to fix this car right the first time?”

I will show you how to dynamically check the circuits live, with the help of a scan tool capable of bi-directional control; one of my favorite tools, a “Fuse Buddy”; a DVOM; and a handy little homemade load simulator (Figure 2 & 2a).

There are load simulators from tool manufacturers that are fancier than this, and some have adjustable loads; this can be made for $35 with standard parts available at Radio Shack.

OK, let’s get started. What do we know at this point? We know that the vehicle sets a code P0753 and that the entire circuit resistance checks well within spec’s, so now we will connect to the circuit through the power supply (fuse) with an ammeter (Figure 3) and command the 1-2 solenoid on (Figure 4).

In Figure 4 you can see 1-2 solenoid is on but there is no current flow. Now how can that be? Remember, “I ohm-checked the entire circuit and it checks OK”. So it must be the PCM right? Well, at this point, it could be, but let’s make sure.

Figure 5

Since we started this diagnosis by using the traditional flow chart, resistance and power checks, we know that there is 12 volts at the transmission. We knew that more than likely that was the case because we only have one code set. Since we’ve looked at the wiring diagram, we know that the 1-2, 2-3 and TCC PWM solenoid are powered from the same wire.

Now we hook up the load simulator to the circuit (Figure 5) and then command the solenoid on with the scan tool, and we get the same reading as in Figure 3: no current flow.

Now we are going to remove the black test lead from the connector (control side of circuit) and connect to a known-good ground (Figure 6). At this point, since the PCM controls the ground side of the circuit, all we need to do is turn the ignition on.

Figure 6

Now we get a reading of 1.1 amps (Figure 7). (Test leads are connected to the load simulator at the 10 ohm resistor) We now know for certain (1) that the integrity of the power-supply side of the circuit is good, and (2) the problem is in the control side of the circuit between the case connector and the PCM, or in the PCM itself.

(Note: if you still had no current flow at this point, you would supply power to the load simulator’s positive lead and recheck.)

Now we are going to move the lead from the known-good ground directly to the PCM by back-probing at the PCM connector and with the scan tool command the 1-2 solenoid on. (Figure 8)

We get the same reading of 1.1 amps. We now have a fool proof diagnosis that the problem lies in the wire or connection between the case connector and the PCM, and we have also proved that the driver in the PCM is capable of handling the circuit current load.

(Note: if you had supplied a separate power and ground wires to the load simulator and PCM and still had no current flow, you can prove that the PCM is unable to control the ground side of the circuit.)

After some disassembly to gain access to the wire loom, I found an improperly routed harness that was smashed under the air box, which houses the PCM. Figure 9 shows the wire that I removed from the loom, and Figure 10 shows the area where I found the problem.

Figure 9

Figure 10

After repairing the wire, we can now test the complete circuit before we reassemble the vehicle. As you can see in Figure 11, we now have the correct current flow when the 1-2 solenoid is turned on, and the repair is complete.

Figure 11

You can use this method of testing on almost any circuit on the vehicle. By using the load simulator in place of the suspect bad component and supplying separate power and ground sources you can isolate the problem and verify the repair, ensuring that you “got the job done right, the first time.”

AX4N (4F50N) Harsh 1-2 Shift

2011-02-01T21:26:00.009-06:00

Written by Jody Carnahan

I received a call from one of our wholesale customers which is a shop that does general repair and transmission work on occasion. He called looking for help on a 2004 Ford Freestar that he could not get to leave his shop. In fact, the vehicle has been to several other shops in the past. He advised me that the transmission had been worked on recently by another shop and that it was now back in his shop. I asked him what the previous failure was and he indicated that it was a problem with a 2^nd gear slip. They had removed the transmission and found the intermediate clutch piston bonded seal was damaged and that was all that was done to repair the unit. Now that they have it all back together, the trans bangs hard on the 1-2 shift. It was not setting any codes and from what the shop could tell everything with the vehicle and load sensors were working properly. I decided to take on this challenge and advised him to drop the vehicle off at our shop.

My diagnostic process started with our normal procedures; hooking up scanner and putting pressure gauge on EPC pressure tap, EPC pressure command on the scan tool and pressure on the pressure gauge appeared to be normal. I put the scanner into the graphing mode so that I could capture and record the pressure control readings during the up-shift through the gears. I did this so I could compare it with a graph that I had on a normal working 4F50N. . We found that on a normal working transmission, the computer would ramp up the epc pressure just before the 1-2 shifts and during the shift it would come back down (see figure 1).

Figure 1

We then graphed the epc pressure on our vehicle with the harsh 1-2 shift and it appeared that the PCM was trying to compensate for the aggressive shift. Because the computer never ramped up epc pressure before the 1-2 shift it stayed steady before and during the shift as you can see in figure 2.

Figure 2

Based upon this information, we concluded that the PCM was working properly and that it was not the cause of the problem. We also ruled out the epc solenoid, because with a pressure gauge hooked to the epc pressure port we were able to confirm that it was following epc command.

Based upon the scanner and pressure gauge data, we needed to start looking for the problem inside the tranny. We needed to identify what component(s) we were going to look at first and also needed to decide whether to try fixing this one in the vehicle or remove it and put it on the bench. We decided to try a fix in the vehicle and went after the valve body, hoping we didn’t have a problem with the channel plate or with an accumulator piston. Prior to removing the side cover and pulling the valve body, I wanted to verify what valve body component could be causing our issue, such as a particular valve, possible check ball in the wrong location, etc. In doing research on the 4F50N, I knew there were several differences in model year valve bodies. Taking a look at the factory manual, I saw that the 2000-2003 model year valve body did not have a 1-2 capacity modulator valve and used a check ball (B10) to orifice intermediate clutch oil to control shift feel. If the B10 check ball was missing, un-orificed oil flow into the intermediate clutch would cause a harsh 1-2 shift. As stated earlier, we were working a 2004 Ford Freestar and this model year went through some changes in the valve body. The 2004-up 4F50N went back to using a 1-2 capacity modulator valve just like the earlier AXODE/AX4S models. Having this information in hand gave us a good direction to start looking and we removed the valve body for inspection. We first inspected the 1-2 capacity valve line up and everything appeared to look normal. The valve stroked fine in the bore and the spring appeared to be in the correct position against the bore plug. The problem was found when we removed valve. The valve had been installed backwards (see figure 3).

Figure 3

With the valve in backwards, the land of the valve blocks off the accumulator causing a harsh 1-2 shift. The valve was turned around and installed correctly (see figure 4), the valve body put back on the unit and we road tested it. The transmission shifted correctly. We also hooked up the scan tool so we could graph the epc command and see if it changed back to having the normal spike before the 1-2 shifts. It looked almost identical to the graph we had one with a good 1-2 shift.

Figure 4

In conclusion, please refer back to the graphs in figure one and figure two. When we ran the graph on a known good 4F50N, it was similar to the graph in figure one. The graph in figure two, harsh 1-2 shift, is the only graph that we have seen with a harsh shift complaint.

While this one test may be inconclusive as the weather we can in fact use this test as a way to determine a harsh shift condition, we will be graphing more vehicles with felt harsh shifts in the future in hopes that this data can be useful within our industry.

I would like to challenge all of the reader of this article to provide feedback to me regarding whether or not the PCM in this case can pick up the harsh shift and adjust the duty cycle to compensate for this condition.

4L60E EC Cubed TCC Control and Adapt

2011-01-01T07:13:00.007-06:00

Written by Richard Middleton, Diagnostician

During the course of helping a co-worker repair a TCC slip, we analyzed some graphs and noticed some interesting info on how the PCM behaves and how it "sees" and adapts for a TCC slip.

All the following graphs were taken on one test drive of a 98 camaro with a 4L60E EC cubed. The required fix was to overbore the TCC regulator valve and the AFL valve and replace them with oversize valves. They both showed significant wear using a wet air test technique. No other repairs were made and the transmission was not removed from the car. The fix isn't the point of this article though, because I'm sure most people reading this article are probably aware of valve body wear issues that cause the TCC slip. The point, is how advanced the computer strategy is, and its ability to "see" and adapt to TCC slip.

These graphs were taken using a PC based scan tool. I like to graph most vehicles in a similar manner as these graphs, with TCC slip and TCC percentage overlapped, and VSS and TPS overlapped, and gear command showing so that you can see how the car is driven and what changes the computer makes based upon input from the driver.

Figure 1, is cold operation with no codes in the computer. This frame is normal. It shows accelerating from a stop, starting at frame #2500, and each gear change with TCC slip stair stepping up as turbine speed changes with gear shifts. At frame 2620-2645, we let off the gas and coasted for a moment, and then we reaccelerate allowing the TCC to apply. In frame 2660 and again at 2690, I step into the throttle more in an attempt to further load the TCC to make it slip. Notice that the TCC slip does go up corresponding to a increase in throttle just after frame 2690, but the computer raises TCC percentage slightly and slip is basically "under control" at 38 rpm by the end of the graph.

Figure 1

Figure 2 shows a warm transmission cruising in 4th. In frame 3400 we raised throttle from 1.8 volts to about 2 volts again loading the TCC. You will notice a slight TCC slip. After coasting through frames 3430-3490 we stepped into it again; the TCC percentage went up to 80% then gradually drops to less than 50% in frames 3490 to 3520. This gradual drop strategy is what I want to point out. It is interesting because I was increasing the throttle, giving more loads to the TCC so you should expect that the computer would give more TCC percentage to hold on the clutch. But instead, the computer ramps the TCC duty cycle down until it creates a TCC slip. It is checking to see at what duty cycle the TCC will slip so it can command it just slightly above the minimum. This is a fuel saving strategy to prolong the mechanical parts by running them at lower pressures. The computer demands as few amps through the solenoid as possible thus applying as little pressure to the TCC. This is an incredibly advanced strategy.

As our transmission continued to warm up, the problem started to show up again. In figure 2, frames following 3530, the TCC slipped with a surge in and out as demonstrated by the spikes on the graph. We could feel the surging, and we could see it as a minor fluctuation on the tach. Notice that following the surging at frame 3585, the computer reacts with a sharp increase in TCC percentage despite no change in speed or throttle. This alone put the TCC back into control.

Figure 2

In figure 3, the car is at normal temperature, and in frame 3025 we're cruising along at about 1.8 volts on the tps and the computer ramps up the TCC percentage from about 15% to about 55%. The TCC slip drops to zero, but, as soon as I load it up a little more, in frame 3060, the TCC slip goes up, and in frame 3080 the TCC lets loose. The computer sees this and immediately reacts raising the percentage from 40% to 75%, and the slip comes back into control and immediately in frame 3100 the computer starts ramping down the TCC again. This results in the slip in frames 3120-2130 and a corresponding command by the computer to increase the TCC duty cycle percentage. Just after frame 3210, I apply additional load and TCC slips and once again the computer compensates dropping the slip to zero. Eventually, after the car is at normal temp, the slip became enough that the computer triggered a TCC code.

Figure 3

Figure 4 was taken on a hot test drive after boring the AFL and TCC regulator and installing oversized valves. You can see at frame 1360 - 1430 that the computer ramps the duty cycle down to 25%. With the unworn circuits on the TCC regulator valve and AFL valve the computer is capable of keeping the slip in line with a 25% duty cycle. This gives lots of room for the computer to adapt and correct the slip.

Figure 4

The computer control strategy is extremely advanced on these transmissions, and learning about them is very interesting. Understanding how the computer behaves and how it adapts to problems is critical in understanding, diagnosing and repairing them.

Getting Connected (And Staying Connected)

2010-12-14T10:19:00.008-06:00

Written By - Ron Clark, Valve Body / Solenoid Tech Director

Being the technical director for the valve body and solenoid department, I’ve seen more than my share of errors and mistakes that have been made by people while working with automatic transmissions. The majority involves electrical components, and a majority of those involve the connectors in some way. Often damage to a connector is done during the disconnection process. We’ve all been told not to wiggle a connector to get it off; that can expand the female pins in the connector, and cause them to have poor, or no connection when plugged back in, i.e. 604’s. Also connectors can have special problems we need to watch out for, such as inserts that may come lose from the solenoid block and stay in the harness connector, like the early E4OD in (figure 1).

In the later E4OD and 4R100, Ford just reversed the problem so that now part of the harness connector may stick in the solenoid block as in (figure 2). Miss either one of these and you may not be able to connect the harness to the block, or the connector won’t have a weather seal and corrosion can quickly set in and cause some serious problems.

The 42LE connector also has an issue with wires flexing and braking, you’ll need to peal back the insulation to see this headache causer, (figure 3) shows you were to look.

These are just some examples to name a few; there is one, however, that if you’re not careful will cause a lot of trouble. That’s the harness connector used on the 45RFE, 545RFE, and the 68RFE. This connector makes you release two locks before you can move the lever down that holds the connector on. The first one is red and is fairly easy to see, the second is black like the connector itself and if you don’t know it’s there you will break it off trying to force the holding lever down. If the lock is broken off and you try and reconnect without it, the connector won’t stay down, and you soon have a condition like in (figure 4) and lots of DTC’s stored in the computer.
(Figure 5) shows a connector with the lock broken off; (figure 6) shows what it looks like the way it should be.

(Figure 7) illustrates the first lock, it’s the red one and it gets pushed down, it holds the second lock in place and you can’t release it until the red one is out of the way.

(Figure 8) shows you the second lock, with the red lock out of the way you can push this lock in and it will release the holding lever, (figure 9). Now simply rotate the holding lever down, and it will lift itself part way off the solenoid block (figure 10).

If that lock is ever broken off, you will need to devise a way to hold the lever securely up in place, and the connector down tight to the solenoid block. If you look inside the connector you will see the weather seal, this has to fit snugly on top of the block connector.

To reconnect, push the connector down until the lever engages the ears on the side on the solenoid block. Rotate the lever all the way up, until it snaps into the lock, this will pull the connector down, now push the red lock back up and you’re all done.

Listen to the Customer

2010-11-01T17:26:00.015-05:00

Written By - Lee Cappen, Diagnostician

By listening to the customer, we can often learn not only want in needs, but sometimes we can pick-up valuable information that helps us solve their problem. In this case, listening to the Customer helped us find an unusual problem that could have been overlooked and led to an expensive and unnecessary repair.

The Customer came into our shop with a 2005 Ford Taurus. He complained that he was having an intermittent jerk at highways speeds. The Customer had gone through the trouble of documenting the times that this jerk appeared, the temperature that it occurred and under what driving conditions he was feeling the intermittent condition.

He also told me that another shop had recently rebuilt his transmission. I took the time to listen to him and ask several follow up questions that would help me to correctly identify the problem. It was very intermittent, and occurred only once every couple of days.

I started my troubleshooting by scanning and found a P0715 stored code. A P0715 is the code for a turbine speed sensor. THis gave me the logical starting point. I checked all the wiring and the connector, they looked good. Next, I cleared the code and went on my first drive. Everything checked out great and during the next two test drives the unit never set another code. I decided to wait until the next day and try it again. At last, after a 15 mile drive I felt a jerk, and the P0715 code returned. I returned to the shop and decided to pull the turbine sensor for a closer inspection. The sensor looked and tested good and ohmed well within specifications. I started to wonder if the other shop could have used the wrong reluctor wheel for this unit? I remembered reading a bulletin produced by our tech department that told us that several cases were found where an AX4S and an AX4N were built with the wrong reluctor wheel. This causes the gap between the wheel and sensor to be either too large or too small. This particular Taurus had a 4F50N installed in it as the AX4S was not available in a 2005 Ford Taurus. Could it be possible that the other shop used the wrong reluctor wheel? I measured the depth of the reluctor wheel and sure enough it was out of spec for a 4F50N. This would have been an easy fix on the older model Taurus with an AX4N or AX4S because they use the same sensor connector, but because the 4F50N uses a completely different connector, the only less costly option was for me to splice in a AX4S connector from an early model Taurus. It sure made the Customer a lot happier than having us to teardown the transmission and replace the reluctor wheel.

After completing the repair I took the car for several test drives with no issues. We released the car to the Customer and followed up with him in about a week, and he told us the jerk was gone and that he was very happy that we listened to him and worked together to solve his problem. That's why it's all about; a happy Customer and one that actually helped us help him. Always take the time to listen to your customer, you just might learn how to help solve the problem quicker and with less costs for everyone.

It's Summer

2010-10-01T16:56:00.008-05:00

Written By - Jerry Huerter, Diagnostician

A 96 Nissan 300ZX came into the shop last summer. Remember, I said it was summer which affects this story later. The customer stated that the check engine light was on and at times would not shift into 4^th gear. I scanned the computer, and it had a P0705 inhibitor switch code. I cleared the code and went for a test drive with the scan tool connected; inhibitor switch data was correct and the code did not reset. I then put the vehicle on a lift and inspected the wiring and connectors, and everything looked good. After talking to the customer we decided to replace the inhibitor switch. The customer picked up the car and said he would let us know if it acted up again. Two days later the customer returned with the same complaint. He said he would leave the car with us for a few days so we would have time to do further testing. Again, I scanned the computer, and the code P0705 was reset. I cleared the code and went for a test drive; the scan data was good and no code reset. After re-inspecting the wiring harness and connectors to make sure I did not miss something, I found everything checked OK. Then I test drove the car off and on for two days and the code never reset. The customer came and picked up the car, and we told him if the check engine light came on again to let us know what type of driving he was doing and where he was driving. He said OK.

The very next day the customer was back at the shop with the check engine light on again. He explained that he had left our shop and drove to work. While driving home from work on the highway that evening the check engine light came on, and the transmission shifted into 3^rd gear. He said it stayed in 3^rd gear the rest of the way home. When he drove his car to the shop the next day he said the check engine light was still on, but the transmission did shift into 4^th gear. I checked the computer for codes, and the P0705 was back. Again I cleared the code and took the car for several long test drives down the highway, but no code reset. Now I was stumped. The customer can get the code to set within hours of leaving the shop, yet I can never get the code to set on any of my numerous test drives.

Upon reviewing the shop manual information it shows that the inhibitor switch gets 12 volts from fuse 19, then as the shift lever is moved to the park or neutral position the inhibitor switch switches this 12 volts to terminal 19 at the TCM so now the TCM knows the shift lever is in park or neutral. When shifted into reverse, voltage is switched to terminal 20 of the TCM, and when shifted into drive voltage is switched to terminal 18 of the TCM and so on for the rest of the gear positions. When the TCM sees no voltage or voltage on one or more of these circuits at the same time it will set a P0705 and inhibit 4^th gear.

(See wiring diagram from ALLDATA)

I disconnected the inhibitor switch and took a fused jumper wire and jumped 12 volts to the harness connector of each one of these circuits and watched the scan tool as I wiggled and pulled on the wiring harness trying to see two circuits on at the same time or one that turns off. As I connected the jumper to the reverse circuit I noticed it sparked. I thought this sparked because the reverse lights are fed from this circuit also. As I connected and disconnected the jumper wire I noticed a light at the front of the car turning on and off. With the jumper connected to the reverse circuit I looked at the front of the car, and the park lights were on. I then went to the rear of the car and found the tail lights on and the reverse lights were not on. When I disconnected the jumper, the park and tail lights went off. Thinking there maybe a problem in the tail or reverse lights, I started checking in that area.

I opened the hatch and saw that the trim panel for the rear lights had been removed and was lying in the back of the car. The wiring and connectors for the rear lights were pulled down and hanging. I printed a wiring diagram and started checking the wires and connectors in the rear lighting location. I found that someone had connected one of the license plate light connectors to the reverse light connector, so with the headlights turned on it fed 12 volts to the inhibitor switch reverse circuit. When the lights were on and the shift lever was in drive the TCM saw 12 volts on two circuits at the same time which caused code P0705 to set and would inhibit 4^th gear. My test drives were performed during daylight hours with no headlights turned on so the code would never set for me. I even drove this car home from work one evening and back in the morning but because it was summertime I didn’t need the headlights turned on. However, the owner of the car worked evenings and when he drove home needed the headlights turned on. That is why the code would set and not shift into 4^th gear every time he drove home from work or at night. In the morning the check engine light would still be on but because the code was only active with the lights on it would shift into 4^th gear. By correcting the light wiring problem I resolved the P0705 code and the no 4^th gear customer complaint.

Honda - No Reverse

2010-09-01T15:07:00.006-05:00

Written By - Dana Deeke, Diagnostician

Recently I encountered a job in my shop that reminded me of the importance of never taking an initial diagnosis at face value. When problem-solving, what you find on the surface doesn't always tell the whole story. That was the case with the 2008 Honda Accord that showed up at our shop one day, coming to us as a sublet from another repair facility. This adds to the challenge, since we didn't have any direct communication with the vehicle owner.

The shop told us that they had replaced the transmission and delivered the car back to the owner. The owner drove the vehicle to her workplace with no issue. Upon attempting to back out of her parking stall to begin her drive home after work, the unit failed to engage reverse. She managed to push the car out of the stall, and was able to engage forward gears and proceeded to drive home.

Once up to highway speeds, it was reported that the 'D' light began to flash, and the upshifts became erratic at the same time. With this in mind, I connected the scan tool and checked codes. I noted a P0986 (solenoid 'E' control circuit high). With the scan tool still connected for monitoring, I set out for the road.

On the road I experienced 2nd gear starts and no converter lockup at highway speeds. Also, as stated, there was no reverse gear engagement. Since solenoid 'E' is responsible for converter lockup, the code fit that symptom perfectly, and since this code was out there, the fail-safe 2nd gear starts also made sense. How did the no reverse complaint fit into this scenario? Some research was in order.

Unfortunately the shop that sent the car to us couldn't tell me whether or not all of these symptoms occurred simultaneously. The only thing that they could tell me was that the owner had driven the vehicle for several days before even having a need to engage reverse. That information was of little use. I then checked for any applicable TSB information that might help. I was looking for something that might show me how these two issues might be related. A TSB search got me nowhere, so now it was time to check into the theory and operation of this solenoid.

As I read about the operating strategy of the solenoids, I learned that the PCM commands solenoids 'A', 'B', and 'E' when reverse gear is selected. Now I could see that solenoid 'E' has an important role in reverse gear engagement, and I was starting to feel like at least one hurdle had been cleared. (Figure 1) If solenoid 'E' is inoperable, oil will not be directed to engage reverse. I was now certain that I found a common link to the problems that the owner experienced.

Focusing on solenoid 'E', there was no clicking sound heard while switching it on and off. The solenoid had proper continuity, so I then shifted my attention to a wiring or PCM issue. The simplest approach was to check the wiring first. A continuity check of the wiring between the PCM and the transmission connector revealed an apparent open circuit. I followed the wiring loom from the PCM down to the transmission, and it was at the connector for the shift solenoids where the root cause revealed itself: a broken wire.

I repaired the wiring and retested the system. As expected, the code was gone and the transmission was operating normally. At the end of the day, it showed me that the OEM uses electronic and hydraulic strategies that change with time, and what we knew a few years ago may not hold true today. Prior to this diagnosis and repair, I had no idea that converter lockup and reverse engagement could be related in any way. I'll keep this in mind when the next puzzler finds its way to my bay.

604 Solenoid Block Mystery Leaks

2010-08-01T15:50:00.005-05:00

Written By - Ron Clark, Valve Body / Solenoid Dept., Tech. Dir.

The 604 / 41TE has been around for some time, and we are all pretty familiar with it; however some things still pose a challenge on this transmission and one of them is leaks.

Over time we have seen numerous fixed in vehicle reports that have solenoid packs being changed for leaking. In response to that, three years ago we made a special test plate so our rebuilt solenoid blocks can be charged with compressed air, and then sprayed all over with a soapy water solution. Any air leakage would then show up as bubbles in the soap, and would expose the leak. Before that, we had an occasional one or two blocks that would leak on the dynos. Now that has gone away, and we don’t see that problem anymore.

What hasn't gone away is solenoid blocks that are being changed and reported as fixed in vehicles for a leak. Of the blocks that we get back, we are usually unable to find any leaks, unless the pack has been externally damaged in some way.

It is my experience that the oil leakage that the block is being blamed for, usually comes from somewhere else and ran down onto or around the solenoid block. There are cooler lines (notorious leakers), a fill port, pressure taps, vent, and an input sensor, all just above and around the solenoid block. Plus, it could be just plain oil spillage from filling the transmission with fluid, easy to do. In any case all these places and possibilities should be investigated thoroughly before just assuming the block is leaking and changing it which is expensive if replaced, and it doesn’t fix the problem.

Oil always runs from the highest point down, to find the source of the leak, follow the oil trail up as far as it goes, always look to the highest possible leak source first. This goes for just about any leak on anything, follow it up as far as the trail goes, and you’ll usually find the culprit.

If you’re not having any luck because the leak trail is hard to see, there are dies available to make it easier for you. Run the transmission for awhile to mix the die in with the transmission fluid, then with a black light the leak trail will show right up. If it happens to be a slow leak, you may need to ask the customer to drive it for a few days then bring it back for a black light inspection.

Illustrated are some of the areas to check for as possible leak sources. Don’t forget to look at the back of the engine as well; motor oil leaks are often confused for transmission leaks.

Along with noises, and vibrations, leaks can be hard to find, but the one thing to remember when hunting them is to ‘Always Look Up’ and follow the trail.

"New" does not equal "Good"

2010-07-01T16:40:00.009-05:00

Written By - John Griffen, Diagnostician

Diagnosis is a challenge for any shop. Sometimes things can get even more complicated by a previous repair, or a part that has been recently replaced. This case involves both of these scenarios. After all, we really want to believe that a new part is a good one, right?

The 2005 Ford Freestar arrived to my bay with 120k miles on the odometer and a complaint of intermittent neutraling and shifting issues with the transmission. A quick pre-road test inspection revealed brown and varnished transmission ﬂuid. Although there was no check engine light on, there was a code stored in memory, P0340. This code is for a camshaft position sensor fault. I wasn’t too concerned with the code itself; the customer had reported that this sensor had been previously replaced by another shop, so it was possible that the technician had forgotten to clear the codes after the repairs. A visual inspection revealed a very new-looking cam sensor.

I cleared the codes and set out for a litt le windshield time. I noted that the transmission had a delayed engagement when cold. It also had a ﬂare on the 1-2 shift. The check engine light did not illuminate at all, and when I got back to the shop I retested for codes and there were none. Based upon the lack of any indication that this could be an electrical issue, and the ﬂ uid condition, I recommended we replace the transmission with one of our remanufactured units.

The reman unit was installed, so I set out for a post-install road test. I went two or three miles to get to the interstate with no issues at all, and the transmission was operating perfectly. As I traveled down the onramp and merged onto the interstate, I got up to cruising speed and still had no issues at all. As I accelerated up an incline in the roadway and as the transmission downshifted to accommodate the hill, the van suddenly nose-dived and lost power. I also heard a strange chirping noise from under the hood when this occurred.

After this initial power loss, operation returned to normal. However, I was able to replicate this condition on an intermitt ent basis over the next eight miles of driving. Within that time, I got it to occur about four more times. In the course of doing this, the check engine light illuminated. I again retested for codes and had found that the P0340 had indeed returned, so I went back to the shop to perform further testing.

As the van idled in the bay with the hood open, nothing seemed out of thee ordinary. If I accelerated the engine the chirping that I had heard on the road returned intermittently. I had an assistant take over the accelerator duties while I poked around the cam sensor with a stethoscope. Sure enough, the noise was being generated by the cam sensor.

I pulled the cam sensor oﬀ of the drive housing to inspect it. There was no sign of internal damage to the sensor. I decided to then pull the drive housing (synchronizer per Ford nomenclature) from the engine so I could inspect it more closely. I brought cylinder #1 to TDC, marked the housing and pulled the synchronizer for inspection.

Inspection revealed a very worn synchronizer shaft and housing. This was allowing the shaft to have lateral movement that was creating internal contact and causing the squeaking noise. After researching this further, I actually found out that this is a relatively common issue for Ford. Also, a genuine Ford cam sensor comes as a synchronizer assembly, with both the sensor and the housing. What usually happens is that the shaft wears and allows the “window” to contact the sensor causing noise, and ultimately, breakage. The previous technician had only addressed the failed sensor without addressing the root cause: the synchronizer.

This case just goes to show that just because the part is new, it doesn’t mean that it’s good. Fortunately we were able to make a happy customer at the end of the story, which is what’s most important anyway.

A Case of Mistaken Identity

2010-06-01T15:41:00.015-05:00

Written By - Dave Finley, Diagnostician

Those of us in the business have seen all different kinds of oddball installations and strange diagnosis that make absolutely no sense at all. There are so many variables that can contribute to a problem and finding the root cause is an ongoing challenge for all of us. To complicate things even further, if you don't have the background story on the vehicle you're trying to fix, you're working with assumptions that can easily get you into trouble. This story is an example of one such repair challenge.

Our shop sees a lot of vehicles that are older. Chances are high that they have experienced a major repair at some point in time. Sometimes they involve used component transplants because the vehicle owner was attempting to save money, or a good-intentioned relative had something lying around that would “fit”. Whatever the case, those vehicles are a reality and sometimes they find our way to us.

The owner of a 1998 Ford E350 gave us a call stating that his van was shifting roughly, and asked if we could take a look at it and diagnose the problem. We set an appointment for him, and when the van was dropped off the only information given was that the van had a rough shift. No more, no less. We gathered the usual information such as VIN, year, make, model, and engine size. We wrote up the repair order and started the diagnostic routine.

The first step in any repair process is to duplicate the concern; so I took off on a road test to see what I could find. I noticed a harsh engagement right away when I shifted the transmission into gear, and as the customer had stated, the shifts were rough and harsh. The shift feel was similar to a Ford that had high line pressure due to a code being set, which would also explain the check engine light being illuminated. A quick scan would hopefully provide the information I needed.

The only hard fault that existed in the system was for the output speed sensor, code P0720, and the CEL was on. With the van on the rack, a quick visual inspection revealed nothing out of the ordinary beyond the fact that it appeared that I was working with an E4OD that doesn't use an OSS. All of the wiring appeared to be intact and in place, nothing unplugged or loose. Something was fishy here, and I was beginning to wonder if anything had been changed or modified on this rig.

Our company uses a proprietary ID system called “SMTC” to create our own parts numbering system for the units we build, and also to identify what transmissions fit a given application. Our application system showed that this van could be equipped with either an E4OD or a 4R100, so at that point I looked to see if the ID tag on the transmission was still in place. It was, and it crossed over to a 4R100. I thought that I was close to solving the issue, because at the time I thought that all 4R100 units were equipped with input and output speed sensors. There just had to be an unplugged harness somewhere for those sensors.

I was wrong. Further research revealed that the 1998 and 1999 model year 4R100 units do not use those sensors. So how could I have a code for components that the vehicle wasn't built with? It wasn't making any sense, so I asked my store manager to contact the van owner to see if we could get more information from him.

Sure enough, the truth came out. It turns out that the engine in this van was transplanted from a 2000 model year school bus. The van's transmission, however, was still OEM. I found out that model year 2000 and newer 4R100 units did in fact use input and output sensors. Now some things were getting clearer, so I decided to take a look at the numbers on the PCM, and there was the answer.

The newer PCM from the donor vehicle had been installed in this van along with the newer engine. Since this PCM was looking for a signal from the OSS (from a 2000 model year transmission), and because there wasn't any signal for it to receive, it was coding P0720, turning on the CEL, and going into failsafe mode. We ordered and installed the correct PCM for the vehicle, no codes, engine ran great, and the transmission shifted perfectly. The correct model year PCM and calibration solved our problem, proving once again that there is no such thing as too much information.

Back to Basics - Strategy Based Diagnosis.

2010-05-01T14:20:00.034-05:00

Written By - Chris Foster, Topeka Store Manager

A friend of mine called and asked me to look at one of his employee’s vehicles. He explained to me that it had already been looked at by two other shops in the area. The issue had been identiﬁed to be transmission related, and if he was going to have to spend any money to repair it, he would feel better having me work on the vehicle. Of course, I said “I’ll be happy to take a look at it, when can he bring it by?” he replied “We’ll be up in an hour or so…….. There is no hurry; he has another car to drive”.

Later that day they showed up to drop off the car. It was a 2002 Volkswagen Jetta GLS with 72,000 miles (picture 1). The owner of the car started to explain the concern he was having; “everything was working great, then one day the check engine light came on, and it started to shift real hard and fast. I took it to ----------, and they said it was either the transmission control module or the transmission. They said if it was the module, it was going to be $2000.00; if it was the transmission $5000.00, plus reprogramming and any wire repairs, or it could need both. I paid them $145.00 for looking at it, but I wanted to get a little more speciﬁc about what it was going to cost, so I took it to ---------. They had it for a week and said they thought it needed a control module, but were not real sure, and asked me to take it somewhere else……… so here I am”. We were eager to accept the challenge and a willing to work on any type of transmission, and since I wanted to be able to ﬁnd out what exactly was going on with it, I said I would give him a call in a day or so with an estimate for the repair.

I went to road test the vehicle, as well as get some preliminary information, and in a short while I was able to verify the customer’s concerns; the check engine light was on and the vehicle shifted abruptly with a shock at each shift point. I brought the car into the shop and checked for anything obvious; raised it up to see if there were any signs of broken wires or leaks. It all looked good, so I hooked up my scanner and it revealed a DTC P0715 Input / Turbine Speed Sensor “A” Circuit. “Well, this ought to be easy enough” I said to myself, but this was preceded by a comedy of errors that I am embarrassed to talk about; but c’mon, we have all been there at one point or another.

Realizing it was a newer transmission, and probably not a lot of technicians have worked on the VW O9A before, it was going to be difﬁ cult to ﬁ nd an accurate diagnostic procedure. To make matters worse, there is an ‘early’ and a ‘late’ design of this model transmission. I was amazed at the amount of information one can ﬁnd on the internet as well as the various subscription services, along with having a very reputable V.W. Dealership in our town; so what could go wrong? I printed off the wire diagram from our subscribed website to get an idea of what I was in for and to be honest it seemed pretty cut and dry. Pin 9 and 10 were the signal wires coming out of the transmission going to pin 09 and 36 at the TCM, which is located under the plenum that covers the wiper motor, (picture 2 and to me that seems like a good spot for water intrusion). The wires were good, and the TCM appeared to be dry, so after about two hours of chasing wires, and taking stuff apart I am to the point of it either needing a module, or the transmission needs to come out.

Knowing I could not call the customer and tell him the same thing the other shop just told him, we decided to take the diagnostics to the next level. I simply raised the car up a bit, put it in drive to let the wheels start spinning, back probed the wires going to the TCM, and found there was no signal coming out of the transmission. I turned the car off, unplugged the transmission, probed the wires going to the ISS9 (Picture 3 and 4), and needless to say the sensor was way out of range and needed to be replaced. I called around to see if the part was available from any source other than the dealer, and it was not. While on the phone with the VW parts department, I asked about the history of the part (in an effort to ensure I was on the right track), “We have never sold one here, most likely because it is an internal part and we would simply replace the transmission, rather than try and repair it… the part is $148.00 and the transmission is $4815.00, I can have either one for you in two days” was the reply I got. Not quite the “OH YEAH … Sell tons of them, in fact we have 4 in stock” I was hoping for: however, I conﬁdently ordered the part, and asked them to fax a picture of the sensor. Fig 244 of Mitchell on Demand was the picture on the fax machine; #2 is ISS #1 IS OSS

Now I had a picture of where the part was located, and the part was on the way. I called the customer and told him what I had found and provided him an estimate for the repair, and while it was unfortunate that is was 11.5 hours labor to replace the part, we were a long way from $5000.00 for replacing the transmission. The repairs were authorized, and the part was a few days away, and our shop started to get busy, so I told him it would be late next week before I could work on it again. With that I moved on to the other cars in the shop.

The part arrived on Thursday morning, with the mental picture burned into my memory from the fax received a few days before, I knew I had to remove the transmission, separate the case and replace the speed sensor just under the pump assembly, bolt the case halves back together and reinstall the transmission, the shop was very busy so it was clear that I would not be able to get on it until late Friday or ﬁrst thing Monday. My plan was to bring the car in on Friday afternoon and get it ready for repairs on Monday; I took the tires off and drained the ﬂuids, which didn’t look too bad.

Monday; got the transmission out ‘ok’ and slid it onto the bench. It looked like the cases were sealed with sealant, so there should be no other parts needed. I separated the cases and there it was, just like the picture I studied. The shop was still very busy, so I decided to replace the sensor, bolt the cases back together, and I would reinstall it after we slowed up a bit; I did tell him late next week after all. I opened the new speed sensor, it matched up perfectly to the one I was replacing, no other checks needed; two bolts and one plug in and I’m done, so I bolted the cases together with assembly adhesive ﬂipped it over, and went on to the next job.

We managed to get back to the install late Wednesday, I got it all wrapped up with $85.00 worth of ﬂuid pumped into it around closing time, ran it on the rack, checked the ﬂuid, shut the hood and did the ﬁnal road test the next morning, only to reveal the same concern we started with, the check engine light came on, it shifted quick and hard by the time I got out of the parking lot. I ran it back in the shop, and the scanner showed DTC P0715 Input/Turbine Speed Sensor “A” Circuit. “Where the hell did I go wrong here?” I said to myself.

Trying to regain conﬁdence in my diagnosis, I came to the conclusion “Of course! The dealer is the only one that can clear this code, I don’t have a VAG! The code must still be stored in the TCM and I can’t clear it” I jumped in the car and drove it to the local dealer; luckily the tech was available for a quick check of the car. We hooked it up to the VAG and it displayed code 17099 Input/Turbine Speed Sensor “A” Circuit, (things are looking up now!) We ran through the same tests I performed a week earlier, and came up with the same results, an open ISS;“I just put a new one in, bought it here as a matter of fact”, he replied (just like I was thinking) “must of got a bad one” and back to the shop I go.

Reluctantly I pulled the transmission back out of the car, slid it onto the bench, separated the cases and placed the faxed picture alongside the sensors to make sure I changed the correct speed sensor, sure enough; it should have worked, but it didn’t. After conferring with our resident electrical expert/service advisor Jerry Temmen, it was determined there is either a bad speed sensor or a bad wire going to the speed sensor OR the wrong picture of the speed sensors in the transmission.

PRSRT STD U.S. POSTAGE PA I D FORT DODGE, IA

PERMIT NO. 733

To make a long story short, the picture that was faxed to us, along with the picture we printed off of our online subscription were of a different version of the same transmission. What the picture shows as the Input Speed Sensor and the Output Speed Sensor, is actually a picture of the Output Speed Sensor and the Intermediate Shaft Speed Sensor. I replaced the Intermediate Shaft Speed Sensor, not the Input Speed Sensor as I had thought. The input speed sensor actually picks up its signal from the K2/K3 (high clutch/reverse clutch) drum at the back of the transmission. In any event, I switched the sensors, put the transmission back in the car, and shipped the vehicle.

Where I went wrong was stopping the diagnosis based on pictures and visually identifying the parts assuming the concern was isolated. If I would have spent ﬁve minutes checking the continuity between terminal 9 and 10 to the (what I thought was) the input speed sensor, it would have read OL, that would have led me to checking the rest of the wires, and eventually ﬁnding the correct speed sensor to replace. In other words, I would have gained the ability to verify the correction prior to me reinstalling the transmission, and would have saved a lot more time than me trying to shortcut the procedure so I could continue working on other cars in the shop.

Don't Forget the Basics

2010-04-01T13:13:00.008-05:00

Written by Jerry Tipton, Diagnostician

When I was asked to write this article I thought, “What vehicle should I write about?” Instead of choosing just one success story that applies to one vehicle, how about writing something that applies to all vehicles? The thought that I want to convey is to pay attention to the simple things and small details alike, both when diagnosing a problem, or when removing and installing a transmission.

With today's vehicles we all know that all of the various subsystems work together to make the vehicle perform properly. Scan tools are a must with computer controlled vehicles, but common sense may play a more important role than meets the eye. Our company has multiple locations, but my shop is responsible for diagnosing and repairing wholesale sales warranty issues. These vehicles come to us from other shops that we have sold carry out transmissions to. I am directly involved with these repairs.

What I often see is that the transmission is not the root cause of the issue, but instead it is the vehicle that is causing the concern. I'd like to share some examples of things that I have discovered while diagnosing these “warranty” concerns.

The Buick Le Sabre...

The customer that called us on this car felt that the transmission was going to blow apart because of the violent shifting that was being experienced. The first step in all of my diagnostic processes (after verifying the concern) is to check the basics first, and that is how this problem was found.

I started with an electrical systems evaluation. What this revealed was that the charging system was running at 18 volts. Knowing that this overcharging condition wreaks havoc with the transmission's electrical components, I unplugged the alternator and the transmission worked perfectly. The fix in this case was to replace the PCM since the charging system output is directly controlled by this module, and wasn't doing its job. One can only guess if the original transmission really needed to be replaced or not.

The Isuzu Trooper...
This one came to us with erratic shifts. An electrical check along with a visual inspection of the vehicle made it apparent that this truck had seen its share of corrosive elements. The challenge with this vehicle was that the concern was intermittent, so based on an educated guess and a dose of intuition I installed an extra ground strap directly to the transmission case and the erratic shifts were gone. The key here is that this was a simple repair to try and should really be done with every transmission replacement in these vehicles, as it is a common concern.

The Ford Bronco...

A car dealer installed a new 4WD switch and transfer case shift motor to fix a “4x4 inop” concern. After performing the basic vehicle electrical system checks, I started diagnosing by checking power to both the 4x4 switch and 4x4 controller. No issue there. I then tested for a voltage signal from the switch to the 4x4 controller; so far so good. Now it was time to check the voltage signal from the 4x4 controller to the transfer case shift motor, and there was NO signal. I hadn't mentioned that this vehicle had been completely restored inside and out, but after tracing the wiring and pulling the drivers seat from the vehicle I discovered that when the seat was installed during the restoration, the seat bolt caught the t-case wiring harness and ripped it apart. This was a simple case of the dealer technician simply replacing parts and hoping to fix it, but instead repairing the wiring was the solution. Shall I go on? Okay.

The Ford F350 4WD...

This final vehicle was the story that inspired me to write this article. The 2001 Ford F350 4WD dually was towed in from the local interstate, and per the customer it quit moving. This is the most damage I had ever seen on a vehicle that was created from a minor cause due to a major oversight. The front drive shaft U-joint broke apart and started a chain reaction of damage that nearly totaled the vehicle! The transmission, transfer case, wire harness, fuel lines, brake lines, frame and under body all sustained some level of damage. Because of this damage, the vehicle stalled and lost its brakes while pulling a loaded trailer. It wasn't clear as to whether the R&R tech missed a bad u-joint or installed one incorrectly, but the one thing that is known is that this customer was left with a very expensive repair because a simple item was not checked or repaired properly.

I have seen PCM'S and TCM's fix vehicles when a replacement transmission did not. There are many other examples I could go into, but I think you get the point. I guess we all think everything is so complicated, but if we just check and take care of the basic things our lives (and our customer's) would be made a lot better. I know some of us have worked in this industry for so long that we can do it with our eyes closed, but maybe we should work on keeping them wide open to keep the customer happy, and earn more repeat business.

Wholesale Carryout Transmission

2010-03-01T15:34:00.014-06:00

Written By - Carman Clayber, Diagnostician

A wholesale carryout transmission can be a great addition to your weekly sales. We try to assist our customer by sharing our years of trouble shooting experience. Since we specialize in transmissions we have more opportunity to learn from the school of hard knocks.

Recently a customer called to get a quote for a 1998 Ford F-150 4X4 with the 4.6L engine and 4R70W transmission. The price was given and we had one in stock. A couple of days later they called and told us they needed the transmission. It was still in stock, but late in the day so arrangements were made to get it delivered to them the next day.

The next day we received a call from the shop that there was a problem. Like fingernails on a chalkboard we cringe. “This transmission is doing the same thing as the old one.” What we have to remember is this is a cry for help. They have a problem and don't know how to proceed. Time to get the vehicle to our shop and put on the diagnostician hat.

Communication becomes critical at this point. We need to know symptoms and codes that were present before they started working on the truck. I knew the old transmission was toast based on the fluid color and condition. However if there is still an issue that told me the transmission was a victim not the culprit.

Arrangements were made to get the truck towed to our shop. The timing worked out great. I had just finished a final road test when it arrived, so I was able to get right on it. We take warranty issues very serious, they take top priority.

I grabbed the paper work & scanner and headed out to solve the mystery. The other shop did not have any information other than the truck barely moved when they got it, so no history of codes. When I plugged the scanner in I retrieved several codes, all of which were solenoid codes. We know this typically means no power to the transmission. Trying to keep it simple I first checked fuses, all okay. Next I went to the transmission and checked the connector. It was plugged in properly, no pins pushed out, no green fuzz. However, there was no power on pin #4 (red wire) confirming my suspensions. Now let’s go to the other end. I checked for proper voltage going to the PCM at pins #71 and #37. These were both okay. Next quick check of pin #87 that supplies power to the transmission, it was okay. Now we have the answer, its a bad wire from the PCM to the transmission. We placed a call to the shop explaining what we had found and to get the okay for further testing and repairs since this was obviously not a warranty issue. They authorized us to find the problem and fix it.

Back at the harness I wanted to check all the wiring going from the PCM to the transmission. Do we need to just run a new power wire or is there more? Guess what? No reading on multiple wires. So we either have a smashed or damage harness. Let’s look. Can't see a darn thing, no room. I went below and disconnected everything and removed the harness from above. A plastic retaining clip had broken and allowed the harness to contact the exhaust. We found a silver dollar area that was now one melted together glob. A short time later after splicing and repairing the wires with connectors, solder, and heat shrink we were all back together. Now to stuff the harness back in without the truck eating my hands.

Back in the seat of the truck, scanner plugged in and voila no codes. I headed out on the road for a comprehensive road test. The transmission shifts great, good TCC. About 20 minutes later I returned to the shop and raised the truck one last time to check for leaks and to make sure the harness was in place. The shop was then called to let them know truck was done and ready to go.

A sense of calm and relief returned and everything was right in the world again.

We have seen this type of issue several times since. It saves a lot of time and grief to really pay attention when doing a checkout. Fluids nasty burnt, slips in the parking lot, yes it will need the transmission replace but just a few minutes to check for codes and hmmm? We may have another issue. Also the harness repair would have taken a lot less time when the transmission was out of the truck. We also need to remember when we get the call “It’s doing the same thing” what they are doing is telling us there is more than one problem and they need our help

Mrs. Miller's Transmission

2010-02-01T15:32:00.013-06:00

Written By - Scott Richardson, Diagnostician

A few weeks ago, Mrs. Miller came in with what she had been told was a transmission concern. She had taken her vehicle to several other places, including the dealer, before bringing it to us. She was very concerned since her after market warranty was only 5 miles away from running out. She stated that her 1999 Dodge Caravan wasn't shifting properly and her transmission range indicator on the dash had a malfunction, and not even the Dodge dealership could find the problem. After performing our Certi-care evaluation, which includes test driving the vehicle, scanning for service codes, and performing a visual inspection, I was unable to find anything wrong. There were no codes, shift points were good, fluid was in good condition, and the range indicator was working properly. Since Mrs. Miller was waiting at this time, I asked if she could leave it with us for a little while to see if we could duplicate her concern. She was unable to at that moment but set an appointment to bring the Caravan back a couple of days later for us to perform Level-1 Electrical Diagnoses, which is beyond our certi-care evaluation.

This time when I started the vehicle I noticed that the digital range indicator didn't circle the park or neutral ranges, all the other ranges were ok. I pulled the van in the shop and when I shifted the lever from drive to park, the drive range stayed circled for a few seconds then all the indicators circled. Well, my first thought was obviously there is a transmission range sensor (TRS) malfunction. I took the van for a short road test and sure enough, the transmission was in failsafe mode, 2nd gear only. Now I was able to verify both of the customer's complaints, but when I pulled the van back into the shop the range indicator started working properly again. I thought it was possible the transmission control module (TCM) would have stored a code since the transmission went into failsafe mode but to my surprise there were no codes stored. I tried the rest of the day, off and on between other appointments to get this intermittent problem to stay consistent long enough to get it figured out, unfortunately I was not able to. Mrs. Miller needed the van back for the weekend because it was the only vehicle she could fit 7 children in, and our rental car was already out. So we scheduled another appointment for Monday.

When Mrs. Miller brought the vehicle back to our shop it sat outside long enough to cool off before I was able to look at it again. When I started the van the TRS was malfunctioning again, so instead of pulling it in the shop I grabbed the scanner and plugged it in. I wanted to see what range it showed to see if the malfunction was just the indicator, or a problem with the range sensor but the Scanner had no communication. I hooked up the Battery/Alternator tester and the electrical/charging system were both normal. Now I'm thinking maybe it's an internal problem with the range sensor, or wiring is shorting to ground between the TRS and the TCM, causing the TCM to power down. I went to Alldata.com and pulled up wiring diagram's for the TRS. Next I ohm tested all wiring circuits between the TCM and TRS, 6 circuits to the TCM and 1 to the power train control module (PCM), no problem found. I plugged all the connector's back together and hooked the battery back up, and turned the key on to see if the TCM would power back up, and it did. I cleared the code for having the battery disconnected then started the vehicle with the scanner still hooked up. After starting the vehicle the Scanner lost communication with the TCM, still in park, I hadn't touched the shift lever or stepped on the brake pedal.

So now the TCM was working before I started the van, after starting the TCM lost communication or powered down. My next step was to go back to the TCM and check all power and ground circuits, again no problem found. All ground's were 0.1 ohm's or less, so I decided to monitor the power circuits at the TCM, pin 56 battery voltage, pin 11 fused ignition, and pin 8, also fused ignition. What I found was pin 56 and pin 11 remained constant whether the TCM was communicating or not. Pin 8 was intermittent. If there wasn't power the TCM powered up, when there was power the TCM didn't power up. In the wiring diagram pin 8 shows ignition so I assumed it would have power when the key was on and when running. Next I went to the ignition switch diagram, according to the schematic, pin 8 goes from the TCM back to a 10 amp fuse #10 under the dash, ( circuit F45 ) then it goes form the fuse #10 back to the ignition switch pin 10, ( circuit A41 ). The schematic shows that this circuit only has power when cranking. At first I thought this had to be a miss print so I decided to cut the wire at pin 8 about 6" away form the TCM, ( so I would have enough room to solder the wire back together later ) and go drive the vehicle and see if the TCM stays on. I drove the van three times, about 12 miles total and cycled the ignition key several times before and after each road test with no problems at all.

Still a little puzzled over the schematic issue of this circuit A41 before the fuse and F45 after the fuse, (pin 8) at the TCM turning the computer off when voltage was present. According to the schematic, if voltage is present after starting at pin 10 at the ignition switch, then the ignition switch has an internal short to power. I called several people I know at dealerships and general repair shops and know one had seen this problem before. Then I called Joe Hurley who is the diagnostician at our Independence location. Tranny Joe, as we call him has been with Certified Transmission almost 16 years and every shop in the area calls him for technical advice. After I explained to him what I had found I ask him if he knew why Chrysler ran voltage to the TCM when cranking. I was shocked when he said "yes I do" he also said he had run into that very same problem some time ago. He said after talking to several Dodge and Chrysler dealership technician's he couldn't get a straight answer from any one, he finally got a hold of a Chrysler electrical engineer who told him that circuit was used to turn off the TCM during cranking to keep the TCM from setting solenoid code's, I would guess due to the voltage drop while cranking. Now it all made since, so If you have an intermittent no communication issue after starting, or the customer complains of an erratic range indicator and the transmission not shifting, after checking battery and alternator condition and operation, check to see you have battery voltage at pin 56 and ignition voltage at pin 11 at the TCM, if so check for ignition voltage after starting at pin 8, if you find voltage there you've found the problem, a short to power most likely a bad ignition switch. You will still need to check the ignition switch unplugged in the run position for continuity between pin 7-C1 battery and pin 10-C1 circuit A41. If you have continuity you have an internally shorted ignition switch, if not it could be a dead TCM. After we replaced the bad ignition switch, I test drove the vehicle and no more problems were found. We did follow up with Mrs. Miller a few days later and she could not stop thanking us for doing such a great job and told us she would tell everyone about Certified Transmission. Like my Grandfather Lucas used to say, "If you don't learn something every day, your not paying attention."

Nasty Burnt Fluids...Check Codes

2010-01-01T15:53:00.008-06:00

Written By - Carman Clayber, Diagnostician

Recently a customer called to get a quote for a 1998 Ford F-150 4X4 with the 4.6L engine and 4R70W transmission. The price was given and we had one in stock. A couple of days later they called and told us they needed the transmission. It was still in stock, but late in the day so arrangements were made to get it delivered to them the next day. The technicians in our shops jump in and do whatever is necessary. This can be from diagnosing a complex electrical issue to dumping the trash, so first thing in the morning I loaded the transmission to deliver it. The shop was just finishing removing it from the truck. I greeted everyone and together we unloaded the transmission. I checked the core for components that need to be transferred like dowel pins and brackets. Everything had been removed so I loaded the core and headed back to the shop. When I got back the core was unloaded and placed on the drain bench. I did not know what was wrong with this unit as I had not taken the original call, however upon draining it YUCK, man did this fluid stink and boy was it black and look at the nice sparkles.

The next day we received a call from the shop that there was a problem. Like fingernails on a chalkboard we cringe. “This transmission is doing the same thing as the old one.” What we have to remember is this is a cry for help. They have a problem and don't know how to proceed. Time to get the vehicle to our shop and put on the diagnostician hat.

Communication becomes critical at this point. We need to know symptoms and codes that were present before they started working on the truck. I knew the old transmission was toast based on the fluid color and condition. However if there is still an issue that told me the transmission was a victim not the culprit.

Arrangements were made to get the truck towed to our shop. The timing worked out great. I had just finished a final road test when it arrived, so I was able to get right on it. We take warranty issues very serious, they take top priority.

I grabbed the paper work & scanner and headed out to solve the mystery. The other shop did not have any information other than the truck barely moved when they got it, so no history of codes. When I plugged the scanner in I retrieved several codes, all of which were solenoid codes. We know this typically means no power to the transmission. Trying to keep it simple I first checked fuses, all okay. Next I went to the transmission and checked the connector. It was plugged in properly, no pins pushed out, no green fuzz. However, there was no power on pin #4 (red wire) confirming my suspensions. Now let’s go to the other end. I checked for proper voltage going to the PCM at pins #71 and #37. These were both okay. Next quick check of pin #87 that supplies power to the transmission, it was okay. Now we have the answer, its a bad wire from the PCM to the transmission. We placed a call to the shop explaining what we had found and to get the okay for further testing and repairs since this was obviously not a warranty issue. They authorized us to find the problem and fix it.

Back at the harness I wanted to check all the wiring going from the PCM to the transmission. Do we need to just run a new power wire or is there more? Guess what? No reading on multiple wires. So we either have a smashed or damage harness. Let’s look. Can't see a darn thing, no room. I went below and disconnected everything and removed the harness from above. A plastic retaining clip had broken and allowed the harness to contact the exhaust. We found a silver dollar area that was now one melted together glob. A short time later after splicing and repairing the wires with connectors, solder, and heat shrink we were all back together. Now to stuff the harness back in without the truck eating my hands.

Back in the seat of the truck, scanner plugged in and voila no codes. I headed out on the road for a comprehensive road test. The transmission shifts great, good TCC. About 20 minutes later I returned to the shop and raised the truck one last time to check for leaks and to make sure the harness was in place. The shop was then called to let them know truck was done and ready to go.

A sense of calm and relief returned and everything was right in the world again.

We have seen this type of issue several times since. It saves a lot of time and grief to really pay attention when doing a checkout. Fluids nasty burnt, slips in the parking lot, yes it will need the transmission replace but just a few minutes to check for codes and hmmm? We may have another issue. Also the harness repair would have taken a lot less time when the transmission was out of the truck. We also need to remember when we get the call “It’s doing the same thing” what they are doing is telling us there is more than one problem and they need our help.