Engine/Transmission (1994 - 1998) shift

[oldbusguy]

trans goes in and out of lockup so i have two ideas one is take a stick of tnt and fix it or put a switch on trans but which wire do you ground to do this this is the 5th trans in 2 years truck has 307000 mi 94 auto but i bet you knew this jack

 

[Axtell3]

Does it go in and out on smooth roads, steady throttle?

one cause is a bad brake switch, ( bouncing on rough roads) make it drop out of lockup. Another could be just hammering the throttle, it was meant to do that...

You could check the voltage at your tps. with a 94, wiring may be a bit off.

 

[oldbusguy]

in and out with steady throttle smooth road

 

[BigPapa]

Still doing it, huh? I thought the PCM fixed it.



Before I went to a 5-speed, I replaced the TPS on mine twice and the brake pedal switch three times (once after the conversion for the cruise control).



Sorry the PCM wasn't the problem.

 

[oldbusguy]

hi scott yes it did this problem just started the od works charging works it fixed all of the problems jack

 

[Axtell3]

Have you tried the POT fix for the Tps? https://www.turbodieselregister.com/forums/12-valve-engine-transmission-1994-1998/156901-tps-myth-buster-5.html

 

[RVPILOT]

lockup

I had the same problem. replaced t p s, same problem. found out later it was due to worn throttle liknkage. solved this by installing a variable p o t. this allows you to dial in overdrive and lockup speed. look on search forums for info. Stormy

 

[oldbusguy]

did that about 3 yrs ago works great

 

[Axtell3]

so you have the pot fix and it's still bumping out of lock up... hmmm

 

[budnate]

another thought Alt may be going buggy and throwing wild/dirty voltalge spikes enough to upset the pcm and trans lockup...



no to long ago another member reported in depth the alt's and his troubles and how he blue printed a new alt to not throw dirty power at his truck.