I think I've narrowed my problem down to the passkey decoder module. I have an 89 GTA with original wiring. The starter does not turn and the security light is on. I have no saved codes. I've checked the resistance after the lock cylinder and it matches the key in all positions. I've grounded the starter enable relay and the car will start and run, but the security light stays on. This points me further down the line to a faulty connection or the module itself.

I am looking for a second opinion before I tear out the dash to get to it.

Thank you

 

This statement has me agreeing that there has to be something amiss in the passkey decoder module , and here's why ;

It is my understanding that in normal operation , if the passkey module detects a different resistance (or none at all) at the key , it will not only kill the starting via the starter enable relay but it will also kill the signal to spray for the fuel injectors from the ECM . In other words , if the system is functioning 100% and for whatever reason doesn't see it's key and puts the security light on steady , jumping the starter should just result in the starter cranking but the engine not starting , if I am correct . The fact that your car starts should be ( I hope ) an abnormality of how your particular module has failed , unless maybe someone has already programmed VATS out of your ECM but left the rest of the hardware in place .... Anyway , I just thought it strange that it did start with the security light on , best of luck with it

 

I forgot to mention that I reprogrammed VATS out of the ECM to eliminate that part of the equation.

 

Guess I nailed that one , eh ?

Anyway , with the ECM spraying the injectors you've got the hard part of the VATS delete done . Now do a good job of putting a decent jumper on the VATS starter enable relay , take the security bulb out of the dash , and call it done .....

 

If you have reprogrammed the ECM and have installed the jumper there should be no reason not to pull out the VATS fuse in the conveyance center.

That should totally shut down anything left of VATS,

also telling you if your system is totally dead.

Your light should go out.