Power Door Locks Description and Operation. Pontiac Demonstrator 1985

For 1990-2009 cars

### Door Lock System Components

The power door lock system consists of the following components:

• | Body control module (BCM)

• | Driver door lock switch

• | Front passenger door lock switch

• | Door lock actuators in each of the doors

• | ICBM (PWR) 15-amp fuse

### Door Lock System Controls

The power door lock system is controlled by the BCM and can be activated by any one of the following:

• | A door lock switch Lock or Unlock actuation

• | A keyless entry transmitter actuation

• | An automatic door lock actuation

• | An automatic door unlock actuation

• | A last door closed locking (LDCL) actuation

### Door Lock Operation

When the BCM detects a transition of either of the door lock switches to the Lock position, it switches the door lock actuator lock control circuit to voltage. Since the lock actuator unlock control circuits are at ground potential within the BCM, the door lock actuator motors transition to the Lock position.

### Driver Door Unlock Operation w/Keyless Entry

When the BCM detects a transition of either of the door lock switches to the Unlock position, it switches the driver door lock actuator unlock control circuit to voltage. Since the door lock actuator lock control circuit is at ground potential within the BCM, the driver door lock actuator transitions to the Unlock position.

The driver door lock actuator unlock control circuit is a dedicated control circuit used only for the driver door lock actuator. This is done so that the driver door may be unlocked by itself using a keyless entry transmitter or an automatic door unlock function, if programmed.

### Passenger Door Unlock Operation w/Keyless Entry

When the BCM detects a transition of either of the door lock switches to the Unlock position, it switches the door lock actuator unlock control circuits to voltage. Since the door lock actuator lock control circuit is at ground potential within the BCM, the passenger door lock actuators transition to the Unlock position.

The door lock actuator unlock control circuits are dedicated control circuits used only for the passenger door lock actuators. This is done so that the driver door may be unlocked by itself using a keyless entry transmitter or an automatic door unlock function, if programmed.

### Driver and Passenger Door Unlock Operation w/o Keyless Entry

When the BCM detects a transition of either of the door lock switches to the Unlock position, it switches the door lock actuator unlock control circuits to voltage. Since the door lock actuator lock control circuit is at ground potential within the BCM, the driver passenger door lock actuators transition to the Unlock position.

### Lockout Prevention

This function is intended to prevent the vehicle operator from locking the doors if the key is left in the ignition and any vehicle door is open. The lockout prevention function can be overridden by the BCM if the BCM receives a door Lock input for longer than 3 seconds.

### Automatic Door Lock/Unlock

The automatic door lock/unlock function is a vehicle personalization feature with the following 4 programmable modes of operation:

1. The automatic door lock feature is disabled.
2. All of the doors lock when the vehicle is shifted out of Park with the ignition ON.
3. All of the doors lock when the vehicle is shifted out of Park with the ignition ON, and all of the doors Unlock when the vehicle is shifted into Park.
4. All of the doors lock when the vehicle is shifted out of Park with the ignition ON, and only the driver door Unlocks when the vehicle is shifted into Park.

The automatic door lock function can only be enabled by the BCM if the driver door switch is in the inactive state -- door closed.

### Automatic Door Re-Lock

The automatic door re-lock function is a vehicle personalization feature that comes from the factory enabled. After an automatic door lock function has occurred, the BCM will re-lock an opened vehicle door only if the vehicle is in gear and the brake is ON.

### Last Door Closed Locking (LDCL)

The last door closed locking (LDCL) function is a vehicle personalization feature that is intended to allow the doors to be locked while passengers are exiting the vehicle. When LDCL is in Active Mode, the BCM will delay locking of the vehicle doors for 5 seconds after all of the doors have been closed. The LDCL function will be overridden if the BCM receives a door Unlock input or a key in ignition input.