For 1990-2009 cars

### Power Door Lock System Components

The power door lock system consists of the following components:

• | Body control module (BCM)

• | DOOR LKS fuse

• | Driver door lock actuator

• | Driver door lock switch

• | GMLAN serial data link

• | Keyless entry transmitter

• | Passenger door lock actuator

• | Passenger door lock switch

• | Remote control door lock receiver (RCDLR)

### Power Door Lock Operation

The DR LCK fuse supplies battery voltage to the body control module (BCM) for the power door lock system. The BCM supplies and monitors a reference voltage to the driver and passenger door lock switches through the door lock switch lock/unlock signal circuit. Each door lock switch receives ground at G300 which is also the ground for the door lock and unlock relays located in the BCM. When a door lock switch is placed in the lock position, the reference voltage is switched to ground and the BCM senses 0.0 volts on the door lock/unlock signal circuit. When a door lock switch is placed in the unlock position, the reference voltage is switched to ground through a 1.5k ohm resistor that is internal to each of the door lock switches and the BCM senses approximately 2.9 volts on the door lock/unlock signal circuit. The BCM interprets what position the activated door lock switch was placed in based on the voltage drop.

The BCM, upon receipt of a lock or unlock switch signal, will switch the appropriate door lock/unlock relay coil control circuit to ground causing the appropriate door lock/unlock relay to energize. With the relay energized, voltage is applied to the door lock actuator control circuit causing the door to either lock, or unlock depending on what command was received from the power door lock switch or remote control door lock receiver (RCDLR). When a power door lock/unlock relay is not energized, the switch contacts are normally grounded through the BCM which provides ground to the appropriate door lock actuator for the lock/unlock function being performed. The power door lock/unlock functions are performed by reversing the flow of voltage through the door lock actuator control circuits. The BCM has three internal drivers for the power door lock system. Driver door unlock, passenger door unlock and all door lock. This is done to isolate the driver door lock actuator so it can be unlocked separately from the passenger door. For additional information concerning keyless entry, refer to Keyless Entry System Description and Operation.

### Automatic Door Lock Operation

This BCM controlled feature can be personalized to driver preference. For more detailed information concerning personalization, refer to the vehicles owners manual.

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 the ignition is placed in the OFF position.

### Unlock After Air Bag Deployment

This feature will unlock all of the vehicle doors 15 seconds after an air bag deployment.