Th350c help.

[colton hicks]

Lately I've been having problems with my transmission. It would act like it would shift to early into third and it would bog down, thing is it shifted at the same speed it always has. I assumed it had a run of the mill th350, I was wrong it has a th350c with the lockup converter. What is happening is it is locking the converter up as soon as it shifts into third I know this because the tach is reading the rpms locked with the speed of the vehicle.. So not having the money to properly repair it at the time I've disconnected the lockup function. It ran great the first two days but now it's doing the same thing. Any ideas, I've disconnected the vacuum module on the firewall it shouldn't be able to lockup, but it is.

[colton hicks]

Ok update I found a diagram of the wiring for it so i traced all the lines to check for loose connections the connection from the fuse box was loose so I tightened it up, it looked like the last owner had done some work to it. But all the other connections seemed pretty solid. So I took it for a spin and no lockup so that was good, but does anyone know how to test the vacuum module on the firewall? Or where to find a new one?

[Boostaddict]

I can't answer your question, but I have a basic question you might be able to answer.  My '80 truck has the th350c and the lock up torque convertor took a dump after I had a co-worker swap the engine for me a year or two ago (truck is rarely driven).  The torque convertor would lock up immediately after shifting to 3rd, causing the engine to bog.  After doing some reading I now suspect that he might have not hooked up the vacuum line to the vacuum switch when he swapped engines.  Is the solenoid on the firewall (drivers side) near the brake booster?  I think I saw a couple solenoids there that were not being used (I assumed from emission stuff that was no longer hooked up). 

Thanks!
Wayne

[colton hicks]

Sorry haven't been on here in a while, but yes that's the solenoid above the booster, thing is if it's not plugged in your converter shouldn't lock up it needs the reading from that vacuum switch to close the circuit. you might have a problem with the tcc solenoid you'd have to run a resistance check.