Circuit Description

WARNING: This page is about a different car, the 2003 Buick Regal and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.

The BCM supplies a 5 volt signal and a ground circuit for the PASS-Key(R) system. This allows the BCM to detect PASS-Key(R) resistance values. Inserting the PASS-Key(R) (with resistor pellet) in the ignition lock cylinder completes the PASS-Key(R) circuit. Contacts in the ignition lock cylinder mate with the pellet contacts. The BCM compares the resistance value of the key pellet to the valid resistance programmed into the BCM. If the proper resistance value is read, the BCM allows the following functions to occur:

The crank relay to energize.
The BCM sends a message through the serial data line to the PCM to allow fuel delivery to occur.

If the resistance value is incorrect, a malfunction is present and a DTC will set.