Power Locks: Description and Operation
AUTOMATIC DOOR LOCKSThe 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 BCM 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).
CENTRAL LOCKING
If equipped with Vehicle Theft Security System (VTSS), all the doors can be locked with the key by using any of the door lock cylinders. Turning the key to the lock position will lock all the doors. If a sliding door is open when this is done, the sliding door will lock when it is closed.
Holding the key in the unlock position, in any door lock cylinder, for less than one second will unlock the individual door for that lock cylinder. If the key is held in the unlock position for more than one second, all the doors will unlock.
DOOR LOCK CIRCUIT PROTECTION
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 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 lock motors are protected with Positive Temperature Coefficient (PTC) device that prevents motor burn out.
DOOR LOCK INHIBIT
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
POWER DOOR LOCK SYSTEM
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 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.
When the BCM receives an input for a lock request (door lock switch, RKE, or door key cylinder switch (with VTSS only)), it will ground the lock relay coil for a specified amount of time ranging from 375 msec - 1 second. If the request is there beyond 1 second, the BCM considers the door lock signal stuck and will turn the relay coil off. Once a door lock signal is stuck, the signal input for that door is ignored until the stuck fault disappears. The unlock signal operates in the same fashion as the lock signal. The door lock switches provide a variable amount of resistance thereby dropping the voltage of the multiplexed (MUX) circuit and the BCM will respond to that command.
Other power door lock features include:
Sliding Door Memory Lock - When the BCM receives an input for a lock request and a sliding door is open, the BCM will turn on the lock relay as described above, and will turn it on again when all sliding doors are closed. NOTE: If the BCM receives an unlock input before a sliding door is closed this action will cancel the memory lock.
Door Lock Inhibit - When the key is in the ignition and in the OFF position, and any door except the rear liftgate is open, all door lock switches are disabled. The unlock switches are still functional. This protects against locking the vehicle with the keys still in the ignition.
Automatic Door Locks - This feature can be enabled or disabled by using either the DRB III or customer programming method. When enabled, all the doors will lock when the vehicle reaches a speed of 15 mph and all doors are closed. If a door is opened and the vehicle slows to below 15 mph, the door locks will operate again once all doors are closed and the speed is above 15 mph.
RKE (Remote Keyless Entry) Interface
The Body Control Module interfaces with the RKE receiver via a one-way serial bus interface. The RKE receiver sends a 0 - 5 volt pulse width signal to the BCM depending on which button on the transmitter was pressed. The BCM controls the door lock/unlock relays and arming/disarming of the Vehicle Theft Security System (if equipped). The RKE receiver is capable of retaining up to 4 individual vehicle access codes (4 transmitters). If the PRNDL is in any position except park, the BCM will ground the interface wire thereby disabling the RKE.
The RKE module can be programmed via the DRB III or customer programming method. The BCM will only allow programming mode to be entered when the ignition is in the on position, the PRNDL is in park position, and the VTSS (if equipped) is in the disarmed mode.
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.
SLIDING DOOR LOCK MEMORY
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, the BCM locks 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.