Mark, I think you have the information that could help me! I've been chasing this demon of an E40D transmission problem for awhile now! I have a 1996.5 E-SuperDuty 7.3 E40D Shuttle Bus. The brake circuit wiring and transmission errors are definitely connected, and also when I use the hazard lights the bus goes to a limp. It happens semi-regularly (most of the times that I drive) and I believe not only the brake lights and hazards but also the blinker have the potential to trick the computer into going into limp mode. At times it was a poor connection, a failed or failing brake light or blinker I thought was part of the issue, and fixing them has made it occur less often. But it still occurs! I called my local ford dealer and asked about recalibrating the PCM to ignore the brake light circuit once the TPS reaches 10% but they said they are unable to help me, since it is OBD and they only work with OBDII at the moment. Any shop (including heavy truck repair) I have asked to read a code for me from my OBD reader has been unable, though i have a fine time getting all the codes with my BAFX bluetooth reader and an android. I am wondering if you are able to suggest someone I could send my PCM to who is able to handle the calibration? Thanks

 

hi monsty,
APTSpeedometer in Minnesota. I sent my psom(speedometer)to him, he had it fixed in 30 min.
lots lf these xmission guys can’t, don’t or won’t diagnose your prob and just sell you a rebuild job, which doesn’t always fix the problem. ( to-my tune of &2500 twice i learned the expensive way.) I now have over 250k mi on eng and no issues w xmissiom since speedometer chip replace and 3rd lite replacement and tranny plug cleaned and replaced. Had i known in the beginning what I know now, the cost would have been abt $85 + a bulb E40D plug and a lil time.
And like I said im not an enginer🤷🏽‍♂️
good luck God bless
gtxx

 

I do not know anyone that does that.

 

Thanks Gtxx! Just to clarify are you saying you think a speedometer is my issue, rather than something about the PCM and Brake light circuit?

 

Can I ask then, Mark, how did you do it?

 

I worked at Ford. We released new software into production to fix the issue. It did not fix existing vehicles, it just fixed the issue in the ones that were produced with the new software.

 

Thanks Mark for your reply. This means there is no "fix" for those of us who are lucky owners of existing vehicles with this flaw, we are just doomed? After reading your comments about calibration I contacted https://cpaddict.com/7-3-pcm-re-flash-calibrate/ to ask if they knew if they could fix this issue, and they responded it sounded more like a 3rd brake light issue (which I don't have installed). I have also heard it can be connected to the electric brake, but I have unplugged it in past tests without a change in symptoms. But a flash or update of my PCM would not resolve the issue... and I take it I can't just swap out the PCM with a 99, or find a tuning chip which can make these modifications?

 

Thanks Mark for your reply. This means there is no "fix" for those of us who are lucky owners of existing vehicles with this flaw, we are just doomed? After reading your comments about calibration I contacted https://cpaddict.com/7-3-pcm-re-flash-calibrate/ to ask if they knew if they could fix this issue, and they responded it sounded more like a 3rd brake light issue (which I don't have installed). I have also heard it can be connected to the electric brake, but I have unplugged it in past tests without a change in symptoms. But a flash or update of my PCM would not resolve the issue... and I take it I can't just swap out the PCM with a 99, or find a tuning chip which can make these modifications?

 

I don't think you can flash these older PCMs, but I've been wrong before.

A '99 computer won't work in the older truck. There were OBS trucks with the fix, you need one of those computers.

 

My original problem was the transmission slamming gear shifts. And I procrastinated swapping out the speedometer that was in my f250 junk truck. But when i did swap the speedometers, the tranny operated shifted flawlessly . Keep in mind this was after 2 unnecessary rebuilds.....doing the same thing.! Until I swapped psom’s . The chip had delaminated and was causing the limp mode compensation and gear slamming prob. Then while checking and securing wiring, i found the xmission plug had deteriorated and naked wires. Installed new plug, still codes and od light on sometimes then off. Removed plug again , super cleaned everything on plug and prongs on transmission as a last resort for tot codes and reoccurring od light prob. I think then i changed the 3rd light .the transmission stopped reving up 300+ rpm when flashers were applied.
Thank God I didn’t have to drop the pan as that was my next move thinking maybe a bad connection or silt causing the code. After i drove the heck out of it like a bat 🦇 outta the fire 🔥 i realized all my issues had disappeared.
sorry i cant remember it all , maybe re read the thread again.
after 2 major hurricanes a tropical storm And a major freeze all inside 6 months, i haven’t been on the forum at all. I hope this helps you.
(thank God my f250 did not get 1scratch 150+mph winds)
gtxx

 

@Gtxx Can you elaborate on "slamming gear shifts"? My E4OD is up-shifting pretty hard. Wondering if you would describe my tranny's shifting as slamming. I have no other tranny problems, and no codes.

 

When I said slamming into gear , i meant gear shifts really really hard, violently slamming into the next gear. Felt like a A solid jerk when it slammed into gear. When i swapped speedometer module from the 7.3 idi td shifted flawlessly. I reinstalled the repaired original speedometer and that was that .
there was also another thread on cleaning and inspecting your plug to the transmission body.
it is wise to check it and the plug wires out for potential broken and naked wires. I had both. One would figure that a reputable transmission mechanic or shop would address that as a routine part of maintenance, not to mention 2 unnecessary rebuilds. (Im still a lil skeptical of whether they were even truly rebuilt) I don’t want to see that happen to anyone.
research, research, clean, clean, and secure wiring. (Don't procrastinate )
hope this helps 👊🏽🙏🏽🤷🏽‍♂️😇
Also i don’t know how long my truck sat up before i got it , but the front and windshield was
Sticking out if the shed in sunlight. Which probably contributed to the psom chip delaminating due to extreme temperature and weather changes.
God Bless
gtx

 

I ended up solving my gear slamming OD flashing P0500 issue by cleaning up some brake light circuitry that was intermittently shorting and failing, as well as taking apart and the psom and cleaning the plugs, sanding the plug contacts on the back of the board. I posted more about it on this thread. https://www.ford-trucks.com/forums/1...p-of-ae-2.html