GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2000 🢒 Grand Prix 🢒 Body and Accessories 🢒 Doors 🢒 Power Door Locks Circuit Description

Automatic Door Lock Features

The body control module (BCM) controls the automatic door locks.

There are three BCM types:

    • BCM type 2
    • BCM type 3
    • BCM type 4

BCM type 2 has the following features:

    • Automatic power door locks
    • Interior illumination control
    • Inadvertent load (battery rundown) protection
    • Chime functions
    • Retained accessory power (RAP)

BCM type 2 provides the following functions:

    • All door unlock
        The BCM unlocks all of the doors when you press UNLOCK on either door lock switch.
    • All door lock
        The BCM locks all of the doors when you press LOCK on either door switch.
    • Last door closed locking
        The BCM locks all of the doors 5 seconds after you close all of the vehicle door when the following actions occur:
       - The ignition switch is in the OFF position.
       - You press LOCK on either door lock switch.
    • Lockout prevention
        The BCM does not lock the doors if you press LOCK on either door lock switch and the following conditions exist:
       - The key is in the ignition cylinder.
       - The driver's door is open.
    • Lockout prevention override
        The BCM overrides the lockout prevention when you press and hold LOCK for 3 seconds on either door. This action locks the doors.
    • Ignition OFF unlock
        The BCM unlocks all of the vehicle doors when you turn the ignition switch from the RUN to the UNLOCK position.
    • Shift into PARK unlock
        The BCM unlocks all of the vehicle doors when you shift the transaxle into PARK.
    • Shift out of PARK lock
        The BCM locks all of the vehicle doors when you shift the transaxle out of PARK and the driver's door is closed.

BCM type 3 has the following features:

    • All of the BCM type 2 features
    • The keyless entry system (RPO AU0)

BCM type 3 provides the following functions:

    • All of the functions provided by the BCM type 2
    • Remote driver door unlock
        The BCM unlocks the driver's door when you press UNLOCK on the keyless entry transmitter.
    • Remote all door unlock
        The BCM unlocks all of the vehicle doors when you press UNLOCK on keyless entry transmitter a second time within 5 seconds.
    • Remote all door lock
        The BCM locks all of the vehicle doors when you press LOCK on the keyless entry transmitter.

BCM type 4 has the following features:

    • All of the BCM type 2 and 3 features
    • The content theft deterrent system (RPO UA6) with remote activation verification and a remote alarm

BCM type 4 provides the following functions:

    • All of the functions provided by the BCM type 2 and 3
    • Key cylinder unlock
        The BCM unlocks all of the vehicle doors when you unlock a door using the door key cylinder.

All Door Unlock

The all door unlock feature allows the following actions:

    • The BCM unlocks all of the doors when you press UNLOCK once on either door switch.
    • The BCM does not unlock the doors when the content theft deterrent (RPO UA6) is armed.

Pressing UNLOCK on either door lock switch sends a ground signal to the BCM through CKT 194. This action causes the BCM to apply voltage in CKT 694 and CKT 294 for 315-385 ms. This energizes all of the door actuators. All of the vehicle doors unlock.

All Door Lock

The all door lock feature allows the following actions:

    • The BCM locks all of the doors when you press LOCK 1 time with all of the doors closed.
    • The BCM delays door locking when the driver's door is open and the key is removed from the ignition switch.
        This action enables the last door locking feature. If you press LOCK on a door lock switch, the BCM sounds the chime 3 times in order to indicate that the last door closed locking is active. The BCM locks all of the doors 5 seconds after all of the doors are closed.
        If you press LOCK 2 times, you will bypass the last door closed locking feature. The BCM locks all of the doors immediately, even if a door is still open.
    • The BCM does not lock the doors if the driver's door is open and the key is fully inserted in the ignition switch. This enables the lockout prevention feature.

If you press LOCK on either door switch, a ground signal is sent to the BCM through CKT 195. The BCM evaluates the last door locking and lockout prevention features in order to determine when it is appropriate to lock the doors. At the appropriate time, the BCM applies voltage in CKT 295 for 315-385 ms. This action energizes all of the door actuators. The energized door actuators lock all of the doors.

Last Door Closed Locking

The BCM activates the last door closed locking feature when the following conditions exist:

    • Locking control mode 3 or 4 is enabled. Refer to Feature Customization further in this section.
    • A vehicle door is open. An open vehicle door causes an open in CKT 49 and CKT 159.
    • The key is removed from the ignition switch. This action disables lockout prevention. This action causes and open signal in CKT 80.
    • LOCK is pressed 1 time on a door lock switch or on a keyless entry transmitter (if the vehicle is equipped with RPO AU0).

When these conditions exists and you press LOCK, the BCM sounds the chime 3 times in order to indicate that the last door locking feature is active.

The BCM locks all of the doors 4.5-5.5 seconds after all of the doors are closed.

Complete the following steps in order to cancel the last door closed locking feature:

  1. Press UNLOCK on a door lock switch or a keyless entry transmitter.
  2. Turn the ignition switch to the ACC or the RUN position.

Press LOCK twice in order to override the last door closed locking feature. The BCM will lock all of the doors immediately with a door still open.

Lockout Prevention

The BCM does not lock the vehicle doors when you press LOCK on either door lock switch with the lockout prevention feature active.

The BCM activates the lockout prevention factor if the following conditions exist:

    • The driver's door is open.
        This causes a ground signal in CKT 159.
    • The key is fully inserted in the ignition switch cylinder.
        This causes a ground signal in CKT 80.

The BCM disables the following automatic door lock features when the lockout prevention feature is active:

    • All door lock
    • Last door closed locking
    • Key cylinder unlock
    • Keyless entry system unlock (if equipped with RPO AU0)

Lockout Prevention Override

Press and hold LOCK on either door lock switch for 3 seconds in order to override the lockout prevention feature. This action causes the BCM to lock all of the doors immediately.

Ignition Off Unlock

The BCM unlocks the doors when the following conditions exist:

  1. The automatic door lock operation mode 3 is enabled. Refer to Feature Customization further in this section.
  2. The transaxle is shifted into PARK.

    3. The BCM detects an open to B+ transition signal in CKT 1872.

  3. The ignition switch is turned from the RUN position to the UNLOCK or OFF position.

Shift Into PARK Unlock

The BCM unlocks the doors when the following conditions exist:

    • The automatic door lock operation mode 4 is enabled. Refer to Feature Customization further in this section.
    • The ignition switch is in the RUN position.
    • The transaxle is shifted into PARK.
        The BCM detects an open to B+ transition signal in CKT 1872.

Shift Out Of PARK Lock

The BCM locks the doors when the following conditions exist:

    • The automatic door lock operation mode 2, 3 or 4 is enabled. Refer to Feature Customization further in this section.
    • The driver's door is closed.
        There is an open signal in CKT 159.
    • The ignition switch is in the RUN position.
    • The transaxle is shifted out of PARK.
        The BCM detects a B+ to open transition signal in CKT 1872.

Key Cylinder Unlock (RPO UA6)

The BCM unlocks all of the vehicle doors when you unlock a door using a door key cylinder.

Unlocking a door using either key cylinder lock sends a ground signal to the BCM through CKT 781. Holding the key in the unlock position for 1 second causes the BCM to apply voltage in CKT 694 and CKT 294 for 315-385 ms. This action will energize all of the door actuators. Energized door actuators unlock all of the vehicle doors.

Feature Customization

Automatic Door Lock Operation Modes

Combinations of the following three features are enabled by the automatic door lock operation modes:

    • Shift out of PARK lock enabled (modes 2, 3 and 4)
        This mode locks all of the doors when you shift the transaxle out of PARK with the driver's door closed.
    • Ignition OFF unlock enabled (mode 3)
        This mode unlocks all of the doors when you turn the ignition switch from the RUN to the UNLOCK position.
    • Shift into PARK unlock enabled (mode 4)
        This mode unlocks all of the doors when you shift the transaxle into PARK.

The four modes enable the indicated combinations of features:

    • Mode 1:
        Automatic door locking and unlocking are disabled
    • Mode 2:
        Shift out of park lock
    • Mode 3:
       - Shift out of park lock
       - Ignition off unlock
    • Mode 4:
       - Shift out of park lock
       - Shift into park unlock

Changing the Automatic Door Lock Operation Mode

Complete the following steps in order to change the automatic door lock operation mode:

  1. Turn off the instrument panel dimmer switch.
  2. Turn the ignition switch to the OFF position.
  3. Remove the MALL PGM fuse.
  4. Turn the ignition switch to the ACC position.

    5. The BCM sounds the chime 1-4 times. The BCM will sound the chime a number of times that corresponds to the BCM type that is installed to the vehicle.

    The chime indicates that the BCM has entered the feature customization mode.

  5. Press and release LOCK on either door lock switch.

    6. The BCM will sound the chime a number of times that is equivalent to the automatic door lock operation mode. A transition past mode 4 repeats the sequence starting with mode 1.

  6. Complete the following steps in order to exit and save the current customization mode:
    7. • Turn the ignition switch to the OFF position.
    • Reinstall the MALL PGM fuse.

Locking Control Modes

Combinations of the following two features are enabled by the automatic door lock operation modes:

    • Last door locking (modes 3 and 4)
        This mode locks all of the doors 5 seconds after you close all of the vehicle doors when the following conditions exist:
       - LOCK is pressed on either door lock switch.
       - The ignition switch is in the OFF position.
    • Lockout prevention
        This mode prevents the BCM from locking the doors when the following conditions exist:
       - LOCK is pressed on either door lock switch.
       - The key is in the ignition cylinder.
       - The driver's door is open.

The four locking control modes provide the indicated combinations of features:

    • Mode 1:
       - Last door closed locking is disabled.
       - Lockout prevention is disabled.
    • Mode 2:
        Lockout prevention is enabled.
    • Mode 3:
        Last door closed locking is enabled.
    • Mode 4:
       - Last door closed locking is enabled.
       - Lockout prevention is enabled.

Courtesy Lights

Illuminated Entry

For vehicles equipped with BCM type 4, the BCM turns ON the courtesy lights when you unlock a door using the door cylinder lock. Refer to Interior Lights Circuit Description in Lighting Systems.

Delayed Illumination

The delayed illumination features is cancelled when you press LOCK on a door lock switch or a keyless entry transmitter. Refer to Lighting System Description in Lighting Systems.