TCC starts locked - stays locked
 

Any ideas what would cause TCC to lock up all the time. This literally happened overnight. One day the truck shifted just fine. The next time I drove it the TCC started to lock up and would not unlock - no matter what gear or speed. Fortunately, I did make it home in one piece. But now the engine will stall immediately once I shift into R or D. Total no-go.
I checked all of the ground wires that I could find. I did install a mystery switch a LONG time ago; it has always functioned correctly. Just want to see if there might be a ground/wire that I've missed OR if maybe a solenoid in the VB is stuck...
Thanks in advance for any helpful ideas!

Pull the TCC/OD connector at the trans and see if it still does it. They operate by bringing in the solenoid to ground instead of adding the 12V. If you have a wire touching ( not the 12V feed ) it will act as if it is applied.

Thanks for the idea...
Pulled what I thought was the TCC/OD connector (the other was for ATF temp), but still stalled when I shifted into D or R. I need to find my shop manual - in a box somewhere after my move.

95 is a 3 wire connector. I don't have a 95 shop manual or I would tell you wire colors. If that was it, then perhaps solenoid valve is stuck open.

did you get this fixed? mine just started doing the same thing! I unplugged the tcc/od and no change. the engine surges and tries to die when I put it in R or D. I have the service manual but I can't find a test for the solenoid! any help would be greatly appreciated!! I did finally add a drain plug to the trans pan so I guess some good came from this:D

Andy, test is done running using a DRB to toggle on and off, not sure if any aftermarket scanners support it or not. When I lost my TC LU, Dave Goerend had me grasp the trans cooler rubber lines and feel for it pulsing while my buddy toggled it with the DRB.

You could do a similar thing by getting a trans connector, and hooking it up to 12V and a manual switch on the ground.

Lot more hassle, but cheaper than a 3K DRB.

My 93 with a non-lockup TC exhibited the same symptoms for a few days. Don't know WHAT the cause was, but the tranny went out about six months later. I SHOULD have changed the tranny fluid and filter when the problem first surfaced. Might have saved myself two grand!

thanks for the info!! I pulled the solenoids off and put voltage on them one at a time. I don't here a click or anything. I do have 30 ohms on the coil so I know they're not open.

Unless something changes I plan to pull the valve body and clean and inspect all the valves and springs. hopefully I find something.

Are you sure your TC isn't shot. That's the way mine acted and it did it overnight. Try backing a trailer up with the TC always locked up, real fun.