Power Locks: Description and Operation

Power Door Locks Description and Operation

Door Lock System Components
The power door lock system consists of the following components:
- Door lock switch, located in the hazard lamp switch in the center of the instrument panel
- Body Control Module (BCM)
- Driver door latch
- Passenger door latch
- Left rear door latch
- Right rear door latch

Door Lock System Controls
The power door lock system can be controlled by any of the following:
- Power door lock switch activation
- Keyless entry lock or unlock command
- A door lock cylinder switch Unlock actuation
- Delayed locking command
- Automatic door lock command

Door Lock and Unlock Operation
When a door lock switch is activated in the lock or unlock position the BCM will receive a ground signal on either the door lock switch lock or unlock signal circuits.
The BCM, upon receipt of a lock switch lock or unlock signal, will supply battery voltage to the door lock actuator lock or unlock control circuits. Since the opposite side of the lock actuator is connected to ground through the other lock actuator control circuit, the doors, fuel filler door and liftgate will then lock or unlock as commanded.

The following three circuits are used to operate the lock:
- Driver door unlock
- Passenger door unlock
- All door lock

The driver door lock actuator is isolated so it can be unlocked by itself using the keyless entry transmitter.

Automatic Door Lock Operation
This BCM-controlled feature can be personalized to driver preference.
The BCM will automatically lock the vehicle doors if the following conditions exist:
- All vehicles doors are closed.
- The ignition is in the ON position
- The vehicle is shifted out of Park.

The BCM will then unlock the doors when vehicle is shifted back into Park.

Power Door Lock Dead Bolt Operation
Vehicles equipped with the dead bolt feature include an additional reversible dead bolt motor contained within each door latch assembly. Each dead bolt motor is wired to the BCM through 2 control circuits; the door lock dead bolt control circuit and the door lock actuator unlock control circuit. To dead bolt a door, the door locks are activated by momentarily applying voltage to the door lock dead bolt control circuits, and ground to the door lock actuator unlock control circuits. Ground to the dead bolt actuators is provided through the door lock actuator unlock control circuits. Once the doors are dead bolted, the mechanical lock/unlock linkage within the door lock actuator is physically disconnected so that the door can not be manually unlocked. If the content theft feature is armed at the same time, the interior door lock switches will not operate the locks.

To undead bolt the doors, the BCM unlocks the doors by momentarily applying ground to the dead bolt motor unlock control circuit. This energizes the rear door unlock relay coil causing voltage to flow through the switch contacts to the door lock and dead bolt motors. Ground for both motors is supplied through the door lock motor lock circuit through the normally closed contacts of the lock relay to ground.

By performing the following actions, the doors can be locked and dead bolted or unlocked using the keyless entry transmitter:
- Press the keyless entry transmitter lock button once to lock all doors, then press a second time within 3 seconds to dead bolt all doors.
- Press the keyless entry transmitter unlock button once to unlock the driver door, then press a second time within 3 seconds to unlock all passenger doors.

Delayed Locking Operation
With any door open and a door lock switch is activated in the lock position, the BCM will give three audible chimes. When the door is closed, the BCM will cycle the internal door lock relay to lock the doors after approximately five seconds. The function can be overridden by activating the door lock switch a second time. The doors then lock even if a door is open.

Lockout Prevention Operation
The BCM will lock all doors and unlock the driver door with a door lock switch lock activation if a vehicle door is open and the ignition key is fully inserted in the ignition. The lockout prevention feature can be overridden if a lock command is received from the keyless entry system.