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) energizes the lock relay coil through a high side drive control circuit. When the BCM receives a lock message voltage is supplied to the door lock control circuit energizing the lock relay coil.