The relearn procedure for resetting the GM Passlock or Passkey security system is fairly straightforward, though it’s a little time consuming. The directions are the same for either system (Passlock has a resister in the ignition switch, Passkey has it in the key).
Why You Might Have To Reset The Vehicle Security System
There is a resistor either in your key, or your ignition switch on the steering column. A resistance value is sent to your BCM (body control module) – which is programmed to accept a certain value. If this resistance changes; because of corroded wires, a degraded or changed resistor, or changing your key lock cylinder – you’ve got to do the relearn procedure.
Reprogramming the System – Step by Step
Step 1 – Attempt to start the vehicle. It will crank, but not run. The security light will be flashing on and off. Leave the key in the ‘run’ position for exactly 10 minutes, then the security light will stay solid or go off.
Step 2 – Turn the key to the ‘off’ position for 10 seconds. Attempt to start the vehicle. Some vehicles will run at this point, although many will require you repeat repeat Step 1 two more times. Make sure turn the key to the ‘off’ position for 10 seconds before each 10 minute cycle.
Step 3 – The vehicle is now ready to relearn the proper code. Turn the key ‘off’ for 10 seconds and then ‘crank’ the vehicle. It should be running now. The security light might stay on solid for several minutes afterwards, depending on your system.
What To Do If This Doesn’t Work
In the even that reprogramming / resetting your Passlock or Passkey VATS system doesn’t work, you could try repeating the procedure; but most likely you’ll need to replace your ignition switch. In some cases the problem could be caused by your BCM (body control module) or poor wire connections (they tend to corrode after a few years, they’re not gold plated – bad move GM).
If All Else Fails – Bypass The Entire System
Many people have decided to bypass the entire Passlock / Passkey system. There are ways to wire in a resistor to ‘hardcode’ the ignition switch but that won’t fix faulty connections or a bad BCM. The only sure way to do this is to purchase the bypass module, which will send a signal directly to the PCM signaling that the proper value is received, eliminating any chance of the security light keeping your car from starting again.