Circuit/System Description
WARNING: This page is about a different car, the 2007 Saturn Sky. However, it is still accessible from the selected car via links, so may be relevant.
When a cruise control function switch is applied, the body control module (BCM) detects a predetermined voltage signal on the cruise control set/coast and resume/accelerate switch signal circuit. The BCM sends a GMLAN serial data message to the engine control module (ECM) indicating that the function has been requested.