Circuit/System Description
WARNING: This page is about a different car, the 2006 Chevrolet Monte Carlo and 2006 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.
The body control module (BCM) activates the high speed communication enable circuit, when the ignition key is in ACC, ON or START. The high speed communication enable circuit wakes up the electronic brake control module (EBCM) for bus communication.