Truck is a very modified 1996 w/ BTS E4OD. 80K on the trans and 139K on the truck.It's in excellent shape..I bought it new. The TC is unlocking. I've had my tech (25 years and 5 star Ford rated) try to run the codes; all that comes up is trans slipping. Tech apparently doesn't have the old software. Replaced solenoid pac and new pigtail. Will disconnect batteries and computer will reset and the truck drives great for around 30-40 miles. Then, TC will unlock/ lock sporadically for a few seconds.Once this starts, it will unlock for longer periods of time. If the TC is unlocked long enough the O/D light goes on and limp mode starts. I recenly had it custom tuned and the tuner told me that the line pressures were excellent throughout numerous dyno pulls. I did disconnect his flip-chip, no change.
Tim, my tech, cleaned all connections. brake lights are functioning appropriately. What sensors should I check? Thanks for any advise
The inputs for determining when to lock and unlock are engine temp, trans temp, vehicle speed, engine speed, and throttle pedal position. I don't know of a good way to check the sensors for a problem like this other than using a good scan tool that can read live data. You need to see if any of those signals is doing something wrong. Also monitor the signal to the solenoid to see if the PCM is telling it to unlock or not.
It also can be an internal hydraulic leak.
Mark Former Ford Automatic Transmission Engineer
ďThe good thing about science is that it's true whether or not you believe in it.Ē ― Neil deGrasse Tyson
Had the truck at a very reputable shop. I dropped it off with the TC unlocking most of the time, but no limp mode. The tech drove it 180 miles and it performed w/o problems. He has the correct software and tells me that all parameters are correct. I'm just gonna' drive it and see what happens.
It could be electrical issue tom. A failing alternator can back feed through the harness and cause symptoms as these, also on my personal truck it was doin similar anytime I stopped the od light flashed and it acted like the brakes were being held, I had to manually shift it to first gear to take off and once I shifted out all was fine. After much searching and trying things I discovered my 8 month old oem start relay was bad and staying on and causing all my problems, replaced it and havent had an issue since