Power Locks: Description and Operation

POWER DOOR LOCKS / REMOTE KEYLESS ENTRY (RKE)
The BCM controls the Power Door Locks via the relays in the JB. There are three individual relays for this system: Driver Unlock Relay, which only unlocks the drivers door, the Unlock Relay which unlocks the other 3 doors, and the Lock Relay, which locks all of the doors.

There are two Power Door Lock Switches (on the driver and passenger doors) which are read by the BCM to control the locks.

The optional RKE module plugs directly into the side of a highline BCM. A lowline BCM does not have a connector for the RKE. The RKE receiver communicates with the RKE transmitters (key fobs), and gives the BCM commands, via a direct serial communications line. The RKE can tell the BCM to unlock the doors, lock the doors, open the flip-up glass, or initiate the panic alarm. The RKE also can be used to change the Customer Programmable Features (such as Enable/Disable Optical Chirp).

The BCM will actuate the Lock Relay for 250 ms if either power lock switch is in the lock position, unless the driver's door is ajar and the key is in the ignition. The BCM will also lock the doors if the RKE lock button is pressed.

The BCM will actuate the Driver's Door Unlock Relay and the Unlock All Relay for 250 ms if either power lock switch is in the unlock position. If the Customer Programmable Features are set to Unlock Driver's Door First, the BCM will only actuate the Driver's Door Unlock Relay when the RKE Unlock button is pressed the first time. If the button is pressed a second time, both the unlock relays will be actuated (2 unlock presses within 5 seconds). However, if the Customer Programmable Features are set to Unlock All Doors, then the BCM actuates both unlock relays every time an RKE unlock button is pressed.

The BCM does not allow rapid cycling of the lock / unlock relays. Once the BCM starts to actuate a lock or unlock relay, it will hold it for 250 ms regardless of someone cycling the switch rapidly.

The BCM will lock the doors if the Customer Programmable Feature for Rolling Locks is enabled, and the PCI bus message from the Powertrain Control Module (PCM) is received.

The BCM also directly drives the Tailgate Lock motor and the Flip-up Glass Release motor. The BCM can reverse the current through the Tailgate Lock motor to lock or unlock the door as required. If the BCM actuates the Flip-up Glass Release motor, the latch on the glass is released, and the window will raise itself under the power of two gas cylinders (struts).

The Tailgate motor will be controlled to the lock or unlock positions exactly the same as the conditions above for the Door Lock Relay. In addition, the Tailgate Motor will be locked for the following conditions:

1. Tailgate Cylinder Lock Switch in the lock position (if equipped).
2. Battery disconnect / reconnect (including pulling and replacing the IOD fuse)
3. Rear Wiper Switch turned on

The Tailgate Motor can also be unlocked with the Tailgate Cylinder Lock Switch (if equipped).


The Flip-Up Glass Release Motor will release the latch if the Tailgate Cylinder Lock Switch is turned to the unlock position (if equipped) or the RKE Flip-Up Glass button is pressed or the BCM "knows" the doors are unlocked and the rear door handle is pulled to the Flip-Up Glass Release position.

This vehicle is not equipped with central locking. The key cylinder lock switches, if equipped, are to disarm the VTSS only.




Refer to Body Control System.
Body Control Module

Refer to The Programmable Communication Interface Multiplex System (PCI Bus).
Information Bus