GaryalpUSA

Transplanted a 95Z drivetrain into a 94 Body. Kept the Theft Deterrent Module with the steering column from the Z so it all matches. I get fuel pump for 3 seconds when I turn the key to run and the starter works in the start position. I also get a constant Security light.

I read where the TDM sends out a 50 hertz pulse width signal on the dark blue wire from the module to pin A25 at the red connecter on the computer. Does this signal show up as 5 volts? I am getting .13v on my meter set at the 20v detent. If that is correct it means the Theft Deterrent module has a bad fuel signal. Is that right????? Any way to measure the hertz on a meter? Thanks for any replys. GA

shbox

You would need a meter capable of reading frequency to look at it. If the PCM was not getting the signal it would have a trouble code 46 for it. The most common problem is the key is not being read. You can easily check that with a meter. TDMs don't seem to be a common failure point.

GaryalpUSA

Thanks Shbox... I was under the impression that the car would not crank also if the key was not being read by the TDM. Is that correct? If not, and it turns out that the fuel signal is bad would a 50htz bypass box work without bypassing the whole TDM system? Think I will insert the proper resistor on the ignition switch wires and see if that helps. Seems like the easiest thing to do at this point.

GaryalpUSA

Went out to the car and disconnected the plug where the two white wires plug into the purple and white wires that go to the TDM. Sure enough there is no resistance reading at the white wires coming from the ignition. Looks like the key bypass mod coming up. I was making a large problem out of a small one. Lot to be said for KISS..... GA

shbox

Hope it turns out that easy.