Circuit/System Description

WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.

The rear passenger door locks are controlled by the body control module (BCM). When a door lock switch is operated to the lock position, the BCM applies voltage to the rear door lock actuator lock control circuit which energizes the lock relay. With the lock relay coil energized, the switch contacts close allowing battery voltage to flow from the DOOR LKS fuse through the relay switch contacts to the left and right door lock/unlock motors. A ground path is provided by the unlock relay controlled output circuit through the unlock relay switch contacts to ground. The process to unlock the rear doors reverses the flow of current. The BCM applies ground to the rear door lock actuator unlock control circuit which energizes the unlock relay coil. With the unlock relay coil energized, the switch contacts close allowing battery voltage to flow from the DOOR LKS fuse through the relay switch contacts to the left and right door lock/unlock motors. Ground is provided through the lock relay controlled output circuit through the lock relay switch contacts to ground.