Certified Transmission - Transletter ®

September 01, 2010

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.

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.


  1. What causes the transmission to grind going into reverse but not engage, then all of a sudden, slam the gears together very abruptly with so much force you expect a chunk of transmission to be laying on the ground cause the van just shook very much from it, and then reverse works good after this. Something is not engageing smoothly, it is engaging by forced pressure it seems.

  2. I can only assume this vehicle is a Honda Odyssey based on the fact that you mention “the van” in the question. That being said, this is fairly common, and the problem starts with a servo body, the cause may be insufficient pressure holding the servo piston in the reverse position. This will allow the piston to drop the reverse selector out of reverse gear creating the bang and grind sensation. Unfortunately this is an internal problem and will require the transmission to be removed from the vehicle.

    But as I stated earlier, I’m just guessing as to what actual Honda transmission you have. There are other Honda units that can grind and bang into reverse and be a completely different problem.

    Your best bet would be to take it to a shop and have it checked out. We here at Certified will do a check for free, so stop by if you happen to live near one of our 13 retail locations.

  3. where does the servo get its oil pressure from directly? Would there be something blocking or making a valve stick that is not allowing the required pressure to be seen behind the piston? If this is a common problem, did honda not have enough clearance in one of the valve bodies, which is causing sticky valves when abit of buildup is happening from not regularly changing the fluid?

  4. On my transmission, the reverse selector ring is not engaging enough of the teeth, the fix was to lathe off some of the reverse apply piston to allow more piston travel, and engagement

  5. My 97 honda civic 1.6L auto trans was driving fine i pulled into gas station and when leaving reverse worked but then when placed into d4 the light started blinkn and i had to manually shift to get home... i took to advance to have the computer test and selenoid b came up... i then took car home and realized reverse will not engage from drive but will when coming from park... i also noticed in my shifter if it is not fully in the d4 position meaning no light showing what gear im in the car drives smoothly until it needs to shift to d4 and if u nudge shifter to the light shows d4 then it will go into overdrive... i took car to transmission shop and they said it was shot but i drove car home and shifted thru all gears smoothly as long as gear shifter light on dash was not showing it was in d4... is this the selenoid? And if my transmission was shot why is it so smooth and no grinding.... please help any honda tech if u have seen this b4

  6. Hello Erika. Most of what you describe points to an electrical malfunction (sensors, solenoids, wiring, computer). While that may be the root of the problem, it is possible that internal transmission damage could have occurred because of this. If the fluid is very dark or dirty, or smells burnt, then internal damage or excessive wear may be a factor.

    I recommend that you take your vehicle to a reputable transmission shop in your area to get a full diagnosis performed. Do this as soon as possible to avoid the possibility of further damaging your transmission. If you are in the Omaha, Council Bluffs, or Kansas City areas our Certified Transmission stores can perform this diagnostic free of charge.