Locks: Description and Operation

POWER DOOR LOCK SYSTEM
When the BCM receives input for a lock request from a door lock switch, RKE or cylinder lock switch (only with VTSS), it will turn the lock drivers on for a specified time of 375 msec. If the request is there beyond 375 msec, the BCM considers the door lock signal stuck. Once a door lock or unlock signal is stuck for longer than 10 seconds, the BCM will set a trouble code and the signal input is ignored until the stuck condition disappears. 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.

DOOR LOCK INHIBIT
When the key is in the ignition and in any position and either front door is open, the door lock switches LOCK functions are disabled. The UNLOCK functions are still functional. This protects against locking the vehicle with the keys still in the ignition. The RKE key fob will still lock the doors as usual. After the key is removed from the ignition or the doors are closed, the power door locks will operate normally.

AUTOMATIC DOOR LOCKS
This feature can be enabled or disabled by using either the DRBIII(R) or the customer programming method. When enabled all the doors will lock when the vehicle reaches a speed greater than 18 MPH (29 KMH) and all the doors are closed. If a door is opened and the vehicle slows to below 18 MPH (29 KMH), the door locks will operate again once all doors are closed and the speed is above 18 MPH (29 KMH).

REMOTE KEYLESS ENTRY (RKE)
The RKE transmitter uses radio frequency signals to communicate with the SKREEM module. The SKREEM is on the PCI bus. When the operator presses a button on the transmitter, it sends a specific request to the SKREEM. In turn the SKREEM sends the appropriate request over the PCI Bus to the:
- Body Control Module (BCM) to control the door lock and unlock functions, the arming and disarming of the Vehicle Theft Security System (if equipped), and the activation of illuminated entry.
- Integrated Power Module (IPM) to activate the park lamps, the headlamps, and the horn for horn chirp.
- Power Liftgate Module (PLGM) to control the liftgate operation (double press).
- Power Sliding Door Module (PSDM) to control the sliding door operation (double press). After pressing the lock button on the RKE transmitter, all of the door locks will lock, the illuminated entry will turn off (providing all doors are closed), and the vehicle theft security system (if equipped) will arm. After pressing the unlock button, on the RKE transmitter, one time, the driver door lock will unlock, the illuminated entry will turn on the courtesy lamps, and the vehicle theft security system (if equipped) will disarm. After pressing the unlock button a second time, the remaining door locks will unlock. The EVIC or the DRBIII(R) can reprogram this feature to unlock all of the door locks with one press of the unlock button. If the vehicle is equipped with the memory system, the memory message will identify which transmitter (1 or 2) sent the signal.

The SKREEM is capable of retaining up to 8 individual access codes (8 transmitters). If the PRNDL is in any position except park, the SKREEM will disable the RKE. The 3 or 6 button transmitter uses 1-CR2032 battery. The minimum battery life is approximately 5 years based on 20 transmissions a day at 84 degrees F (25 degrees C). Use the DRBIII(R) or the Miller Tool 9001 RF Detector to test the RKE transmitter. Use the DRBIII(R) or the customer programming method to program the RKE system. However, the SKREEM will only allow RKE programming when the ignition is in the on position, the PRNDL is in park position, and the VTSS (if equipped) is disarmed.

PANIC FUNCTION
Pressing the panic button on the RKE transmitter will cause the headlamp relay, the park lamp relay, and the horn relay to pulsate, which in turn will cause the exterior lamps to flash and the horn to sound intermittently. It will also cause the courtesy lamp relay to actuate, turning on the courtesy lamps. Pressing the panic button again stops the headlamps and the park lamps from flashing and the horn from sounding. However, the courtesy lamps will remain on until either the BCM times out lamp operation or until the ignition is turned on. The panic feature operates for three minutes at a time, unless the operator cancels it, or the ignition is turned on.
Actuating the headlamp, horn, park lamps, and courtesy lamps with the DRBIII(R) will verify if the circuits and the Integrated Power Module are OK. If the panic feature is still inoperable with all transmitters, it will be necessary to replace the SKREEM. If the function is inoperable with just one transmitter, then replace only that transmitter.

ROLLING CODE
The rolling code feature changes part of the transmitter message each time that it is used. The transmitter message and the receiver message increment together. Under certain conditions with a rolling code system (pressing a button on the RKE transmitter over 255 times outside the receiver range, battery replacement, etc.), the receiver and transmitter can fall out of synchronization. Note: The lock function works from the RKE transmitter even in an out of synchronization condition and therefore it could be verified by pressing the LOCK button on the RKE integrated key. To re-synchronize, press and release the UNLOCK button on the RKE transmitter repeatedly (it may take up to eight cycles) while listening carefully for the power door locks in the vehicle to cycle, indicating that resynchronization has occurred.

PROGRAMMABLE DOOR LOCK FEATURES
- The RKE can be changed to unlock all doors with one press
- The Automatic Door Locks can be enabled/ disabled
- Auto Unlock on Exit can be enabled/disabled
- RKE horn chirp on lock can be enabled/disabled
- RKE optical chirp (turn signal lamps) can be enabled/disabled
- Program a new RKE transmitter.
- RKE linked to memory (if equipped with memory system) enabled/disabled (DRBIII(R) only). Allows memory to be operable only from the driver door switch.