Circuit/System Description
WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The body control module (BCM) controls the Run/Crank relay by applying voltage to the circuit. The Run/Crank relay is energized when the ignition switch is in RUN or START, or when a remote start is requested.