Engine/Transmission (1994 - 1998) Torque convertor locking and unlocking

[Warhorse]

My torque convertor locks and unlocks as I'm driving along, like it can't decide what it wants to do. I took the truck to the shop that rebuilt the transmission two years ago (reputable shop, does very good work, honest) and he made some adjustments to the throttle position sensor. He didn't charge me, but warned me that he thought something else might be causing the problem. Things were fine for about 500 miles, then it started happening again. I took it back, and after testing several things, the trans guy concluded that the p7100's throttle shaft had worn to the point that it was moving around--enough that the throttle position sensor was getting confused and unable to tell the convertor whether to lock or unlock. So two questions:
1. does this seem plausible?
2. can I do anything about it, short of a new/rebuilt pump?

The trans guy doesn't rebuild or install injection pumps, so I don't think he's truing to pull anything. He has a good reputation, anyway. The truck has 380,000 miles on it.
Thanks
Paul

 

[Bob4x4]

Yes the linkage can wear so bad that the sensor will not even move. I would drive the truck with a scanner connected to see what is happening real time. There are other things that can cause the symptoms

 

[Axtell3]

What happens is the bushings in the linkage wear out. Cheap and easy fix. Goerend has a you tube video of the what why and how. http://www.youtube.com/watch?v=j4v3hDs4VKQ

 

[Bob4x4]

On high mileage trucks it goes way beyond the worn bushings. I have had to build up the shaft and machine down the tip that rotates the sensor itself

 

[Warhorse]

Ok--I watched the video (thanks Axtell3), then I checked the shaft. Just like in the video, it was flopping around. I removed the assembly, and found that one of the bushings was completely destroyed. I'm picking up a new set of bushings tomorrow, and will see what happens.

 

[Jfam]

Hope that solves your problem. I had the same thing on my 94 (now 300k and 500 hp. . ) I replaced 4 TPS's over the years, but what finally (apparently) solved the problem was replacing the PCM.

 

[Axtell3]

Ok--I watched the video (thanks Axtell3), then I checked the shaft. Just like in the video, it was flopping around. I removed the assembly, and found that one of the bushings was completely destroyed. I'm picking up a new set of bushings tomorrow, and will see what happens.

On mine it was only occasional, but I did the bushings, and cleaned everything up. It was a good thing.

 

[Warhorse]

Installed new bushings and a new TPS (the old one fell apart in my hands when I removed it), drove ten miles on the freeway, and everything is back to normal. No more hunting/locking-unlocking. I'll drive it more, though, to make sure. Thanks everyone. The video was really helpful.