Hope you experts can help me. My tranny started acting up so I took it to a reputable transmission shop for repair.
Symptoms;Shifts very hard 1st to 2nd. Light flashes on overdrive button.
The following is what has been done at the transmission shop.
Computer failed to read codes. Sent out to rebuild. After rebuild, codes read FIPL needs replace. Done and gives good readout. Trans control replaced, speed sensor replaced, checked all associated wiring and plugs as well as ground. Dropped pan, changed fluid and filter. No parts in pan. Tech says pan and fluid looked good. Replaced coil pack.
After all that, this is what is happening..Clear all codes. FIPL reading good. No flashing light on shifter. It feels like it is shifting from 1st to 3rd, then back to 2nd. Still shifting hard and indicator light starts blinking again. He is going to read computer again. At this point, he suspects a mechanical problem in transmission but is reluctant to remove and tear down.
I hope you experts have something more for me to do. We have run out of thoughts. Help please
Thank you

 

Big mistake #1. How would one know that the trans needed to be rebuilt? It could have been a computer problem. If it's flashing the OD light and there are no codes that can be a bad computer.

I don't know what a trans control is. Can you explain? How was the wiring checked? Electrically, or with the Mark 1 eyeball?

Coil pack? On a diesel? Or is this a gas engine? And what led to this? Or do you mean something in the transmission? I don't know of anything in the trans I would call a coil pack.

I wouldn't remove and teardown, either, unless I had some evidence pointing towards that. The stored codes may have that evidence.

But if he thinks it's mechanical, and he built the trans, then it's on him to find and fix the problem that he caused.

 

Sorry Mark. Guess I wasn't clear. We sent the computer away to be rebuilt, not the transmission.
Trans control is bad word. I mean the neutral control switch? on the side of the tranny.(maybe that also is incorrect word)
He said he checked wiring with continuity and visual damage.
Sorry again. I'm trying to relay what he told me (I am not a transmission mech). What I meant is solenoid pack in the transmission (it is a diesel)
He ran the truck down the road again clear of codes and came back with code #23 no input to the PCM from the sensor on the back of the speedometer. The speed sensor on the differential is new. He says it is functioning properly. We are sending the speed sensor away to be rebuilt (the one behind the speedometer).
I hope this will cure the problem.

 

Tom, I had a similar issue as the one you are describing in my pickup (it's a 96 F350 with a 7.5 and E4OD) I had the PSOM (computer board behind the speedo) rebuilt on mine and it completely cured the issues I was having. There is a thread on my experiences around here somewhere.

 

That's what we're hoping. Nothing left electronically to be changed.

 

That makes a lot more sense.

It's called the MLPS (Manual Lever Position Sensor) or the TRS (Transmission Range Sensor.)
That's good.
There is a good chance it will. That part is called the PSOM. I forget what that acronym stands for. They are not very reliable. It is probably your problem.

 

Thank you Mark for your input. Hope that does it. The rest of the truck is in perfect mechanical condition as well as looks. I plan on keeping it for a long time.


Tom D

 

Tom D, Did the rebuild of the speed sensor (PSOM) fix your problem? I am having he same issue and have checked everything you have, except have not replaced the PSMO.