1991 F250 Trannie
 

Hi
My f250 4x4 5.8lt has a trannie problem ,When starting from a stop the trans shifts thru all the gears in the first 100 yds and then lugs .If i give it more peddle it will downshift , so if im driving normal it wants to lug out .Have put in new TPS and trannie was serviced with new pump seals/ etc new fluid any ideas would be greatly appreciated

THX Allan

What transmission does it have? C6 or E4OD?

E40d the od button is on the dash
Thx allan

Probably irrelevant but I had a similar problem on my chevy 2004R trans and it was caused by the shift solenoid as I remember.

Okay, it's an electronic transmission. You need to scan the EEC (OBD1) for trouble codes.

Ok Will do tommorrow
Thx allan

Hi
Only code that shows up is 11

Allan

The PCM is getting a signal that the transfer case is in 4x4L. The trans will shift MUCH sooner when in 4x4L. There is a wire from the a sensor on the transfer case to the PCM that gets grounded when it is in 4x4L. You have either a short to ground in the wiring or a bad sensor in the transfer case.

Hi Mark
What would you suggest for a fix . Can i start by replacing the tc sensor ..?? Is the sensor a internal thing ??
I imagine if i try to trace the wire its all covered up ??

Thx Allan

Tracing the wire is almost always a waste of time. You need to check it for continuity, short to power, and short to ground. I'm not an expert on where the sensor is located on the transfer case. I think it's external. It should be an open circuit when not in 4x4L and have continuity when in 4x4L.

Thank You Everyone for the help
Will do what mark suggested and till we meet again Drive Safe

Allan