Ian, Can you give us some clues as to exactly how the TDM (theft deterrent module) works on GM cars? Several of us want to remove these rather troublesome devices on our project cars.
In particular: (1) is the passkey recognition system the only input which trips the TDM, or are there others? (The function of the door lock circuitry is a little vague)
(2) We can bypass the resistor sensor with a precison resistor. That will solve some of the problems, but are there other steps that should be taken?
(3) At some future moment, the TDM may fail, and a functioning one may not be available...Is it possible to get rid of this altogether?
(4) Is the cranking fuel signal to the ECM from the TDM really a square wave, or does this terminal on the TDM just go to ground? Can one force the ECM to give fuel during cranking without having to use the TDM signal?
We all would appreciate any help you might be able to give us in getting rid of this quirky piece of electronic overkill..
Thanks