Diagnostic Aids
WARNING: This page is about a different car, the 2002 Buick Regal and 2002 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
The BCM detects the ignition switch position and sends the appropriate power mode message to the other modules. The BCM must be connected to the class 2 serial data circuit for any other module to communicate with the scan tool.