Power Locks: Description and Operation

POWER DOOR LOCKS DESCRIPTION AND OPERATION

DOOR LOCK SYSTEM COMPONENTS
The power door lock system consists of the following components:
- Body control module (BCM)
- Driver door cylinder switch
- Driver door lock switch
- Front passenger door lock switch
- Door lock actuators in each of the doors
- IBCM (PWR) 15-amp fuse

DOOR LOCK SYSTEM CONTROLS
The power door lock system is controlled by the body control module (BCM) and can be activated by any one of the following:
- A driver door cylinder switch lock or unlock actuation
- A door lock switch lock or unlock actuation
- A keyless entry transmitter actuation
- An automatic door lock or unlock actuation
- A last door closed locking (LDCL) actuation

DOOR LOCK OPERATION
When the body control module (BCM) detects a lock signal from one of the switches, or from the keyless entry transmitter, 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 body control module (BCM) detects a unlock signal from one of the switches, or from the keyless entry transmitter, 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 body control module (BCM) detects a unlock signal from one of the switches, or from the keyless entry transmitter, 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 body control module (BCM) detects an unlock signal from either door lock switch, 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.

DRIVER DOOR CYLINDER SWITCH OPERATION
The passenger doors can also be locked or unlocked while manually locking or unlocking the driver door with the door key. To operate the feature, the door key is inserted into the driver door key cylinder and turned either clockwise or counterclockwise. To simultaneously lock the driver and passenger doors, the key is turned clockwise once. To unlock the doors, the method of operation is slightly different. The key is turned counterclockwise once to unlock only the driver door, then turned counterclockwise a second time within 3 seconds to unlock the remaining doors.

If the door key is turned counterclockwise a third time, the rear deck lid will open.

The driver door cylinder functions are controlled by the body control module (BCM) and the driver door lock actuator. For the feature to operate, the BCM supplies voltage to the actuator via the driver door key switch signal circuit. Two additional ground circuits and the door cylinder switch are built into the actuator. One of these additional ground circuits has a 500 ohm resistor. When the door key is turned to the Lock position, the door key switch signal circuit is grounded through the driver door lock actuator and the BCM interprets the flow of voltage as a door lock request. When the door key is turned counterclockwise, the door key switch signal circuit is grounded through the 500 ohm resistor and the driver door lock actuator and the BCM interprets the limited flow of voltage as a door unlock request.

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 body control module (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 body control module (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 body control module (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 body control module (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.