Ok, this is in my 86 SC in the sig. The tranny was rebuilt recently, No complaints on the rebuild, but he didnt fix the lockup issue i had, the rebuild did not cover anything electrical. So, I replaced the TC soeleniod, that didnt work, then I found a huge vacuum leakfixed it and out of nowhere it started to work, almost. It will enguage and stay, but at low speeds and sometimes at highway speeds it will bounce n and off. What i need to know is, what factors play the roll in telling the ECM to call for lockup. And what terminals do i use to put my meter on to see if the ECM is calling for it. Cause if the ECM isnt looking for lockup, that is telling me that there are other problems to correct.

Any help would be appreciated, the car is in the sig, so you know what mods i got.

 

There should be a TAN/BLK wire that goes from the computer to the TCC. The computer grounds this wire to lock it up. Use a DVM, one probe to ground, one to this wire.

 

The ECM looks at a few variables to determint lock-up engagement/disengagement.
Vehice speed
%TPS
Which gear the car is in
Brake engaged/disengaged