Power Locks: Description and Operation

INTRODUCTION
The Body Control Module (BCM) locks or unlocks the doors when an actuation input signal from a door lock switch or Remote Keyless Entry Module (RKE) is received. The BCM signals lock and unlock relays in the Junction Block to actuate the door lock motors. The front doors, sliding door(s) and liftgate are equipped with actuator motors to lock or unlock the latch mechanisms. The front door lock actuator motor is not serviced separately from the door latch. The BCM locks the doors and liftgate automatically when the vehicle is driven beyond the speed of 25.7 Km/h (16 mph). The automatic door lock feature can be disabled if desired. All doors and liftgate can be locked or unlocked using mechanical button or key cylinder methods.

SYSTEM OPERATION
Automatic Door Lock Feature
The vehicle comes with two options for power door locks:
- Rolling automatic lock (ENABLE), doors automatically lock at approximately at 25.7 Km/h (16 mph).
- No rolling automatic lock (DISABLE), doors do not automatically lock when the vehicle is moving.

The ECM is equipped with a disable feature to stop the speed sensitive automatic door locks from functioning. The DISABLE feature can be switched ON or OFF as desired. When the system is DISABLED the door locks will operate normally, but will not lock automatically when the vehicle is rolling. When the door locks are ENABLED the door locks will automatically lock when the vehicle is moving at about 25.7 Km/h (16 mph).

Door Lock Circuit Protection
The BCM controls the door lock relay's operation. If the door lock switch is actuated continuously for more than one second the BCM will interrupt the relay circuit. The door lock system is protected by a 40 amp fuse located in the Power Distribution Center (PDC). The LOCK and UNLOCK relays are located in the Junction Block. The Power Distribution Center is located along side of the battery The lock motors are protected with Positive Temperature Coefficient (PTC) device that prevents motor burn out.

Door Lock Inhibit Feature
The BCM cancels out the door lock switch actuation, when the key is in the Ignition Switch and a door is open. After the key is removed from the Ignition Switch, or the doors are closed, the power door locks will operate normally.

Sliding Door Lock Memory
When the Body Control Module (BCM) receives a LOCK request and one or both of the rear doors are OPEN, and the key is not in the ignition, the BCM will activate the lock relay again when it receives a door closed signal from the side door ajar switches.

The door locks on the sliding door(s) can be actuated when the door(s) are closed. If the sliding door(s) are open when the door locks are actuated, the BCM will hold the lock command in memory until the door(s) is closed. When the door is closed and the door jamb terminals make contact, signaling the BCM to lock the sliding door(s) automatically Actuating the door lock switch to the unlock position before the sliding door(s) are closed will cancel the lock request.