Hot Off the Wire

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.

Simple Wire Problems

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.”

Chrysler Transmission Range Sensor

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.

Cooler By-Pass

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.

Verify the Systems Before Condemning the Transmission

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.

Solenoid Operating Pressures

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.

Manual Transmission Fails due to Hydraulic Error

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.

Why Resistance Checks Don’t Always Work

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.

AX4N (4F50N) Harsh 1-2 Shift

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.

4L60E EC Cubed TCC Control and Adapt

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.

Getting Connected (And Staying Connected)

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).

Listen to the Customer

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.

It's Summer

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.

Honda - No Reverse

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.

604 Solenoid Block Mystery Leaks

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.

"New" does not equal "Good"

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.

A Case of Mistaken Identity

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.

Back to Basics - Strategy Based Diagnosis.

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”.

Don't Forget the Basics

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.

Wholesale Carryout Transmission

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.