GM Service Manual Online
For 1990-2009 cars only

Press a front power door lock switch in order to lock or unlock all of the doors in unison. You may also operate each lock manually.

Door Lock/Unlock Actuator Circuits

The reversible actuators control the power door locks. The power door electrical system controls the actuators by applying battery voltage to 1 terminal and ground to the other terminal. The body control module (MALL) supplies this battery voltage and ground when the module receives an input signal from a front power door lock switch. Normally, the MALL module connector C1 terminals  A and C are both at ground. The MALL module control at connector C1 terminal C switches to battery voltage in order to lock the doors. The module provides battery voltage to all of the actuators on CKT 295 (GRY). The opposite side of each actuator is connected on CKT 294 (TAN) to the MALL module connector C1 terminal A. The MALL module connector C1 terminal A is still at ground. The actuator in each door runs in order to move the door locks to the LOCK position. The MALL accomplishes the unlock function in the same way. However, for unlock the MALL provides battery voltage on CKT 294 (TAN) while holding CKT 295 (GRY) at ground. The door lock actuators are usually powered for just a moment. If the door lock actuators remain on, an electronic circuit breaker in each actuator opens in order to protect against damage. Each circuit breaker has a positive temperature coefficient (PTC) which resets automatically when voltage is removed from the actuator.

Door Lock/Unlock Switch Circuits

The front power door lock switches provide the input signals to the MALL module at the following two terminals of connector C2:

    • Terminal C6
    • Terminal C7

Pressing a front power door lock switch to the LOCK position connects CKT 780 (RED/BLK) through the switch to ground CKT 1250. CKT 780 grounds the MALL module connector C2 terminal C7 in order to provide the door lock input signal. Pressing a front power door lock switch to the UNLOCK position provides a ground input signal in the same way to the MALL module on CKT 781 (ORN/BLK) at connector C2 terminal C6.

Automatic Door Locks

Pontiac vehicles without keyless entry are equipped with the automatic door locks. CKT 275 (LT GRN) from the park/neutral position switch to the MALL allows this function. CKT 275 (LT GRN) provides battery voltage to the MALL module connector C2 terminal D6 whenever the gear selector is in the PARK position. The MALL module commands the doors to lock under the following conditions:

    • The left door is closed.
    • The vehicle is in RUN.
    • The gear selector is shifted out of PARK.

If programmed to do so, the MALL module unlocks the doors when the gear selector is put back into PARK.

Circuit Operation--Vehicles with Keyless Entry

Use the following procedure in order to lock and unlock the door:

    • Press a front power door lock switch in order to lock or unlock all of the doors in unison.
    • You may operate each lock manually.
    • Press the UNLOCK button on the keyless entry transmitter once in order to unlock the left front door only. Press the UNLOCK button again within 5 seconds in order to unlock all of the doors. Press the UNLOCK button again within five seconds in order to unlock the fuel door (Pontiac only).
    • Press the LOCK button on the keyless entry transmitter in order to lock all of the doors. Press the LOCK button on the keyless entry transmitter in order to lock the fuel door (Pontiac only).

Door Lock/Unlock Actuator Circuits

The reversible actuators control the power door locks. The power door electrical system controls the actuators by applying battery voltage to one terminal and ground to the other terminal. The MALL supplies this battery voltage and ground when the module receives a door lock or unlock input signal. Normally, the following MALL module connector C1 terminals are both at ground:

    • Terminal C
    • Terminal A

The MALL module control at the connector C1 terminal C switches to battery voltage in order to lock the doors. The module provides battery voltage to all of the actuators on CKT 295 (GRY). The opposite side of each actuator is connected to the MALL module connector C1 terminal A. The MALL module connector C1 terminal A is still at ground. This grounded circuit path is CKT 694 (TAN) for the LH front door lock actuator. The following components are the grounded circuit path:

    • CKT 694 (TAN)
    • The normally-closed contacts of the LH front door lock isolation relay
    • CKT 294 (TAN) for the other three door lock actuators
    • The fuel door release solenoid (Pontiac only)

The actuator in each door runs in order to move the door locks to the LOCK position. In order to unlock the doors, the MALL module accomplishes the unlock function in the same way. However, the RFA-controlled LH front door lock isolation relay in this circuit allows for the following three methods of unlocking:

    • Only the LH front door locks
    • All of the doors unlock
    • Fuel door unlocks (Pontiac only)

Pressing the UNLOCK button on the keyless entry transmitter provides an unlock signal to the following components:

    • RFA module
    • MALL module

The RFA module turns on the output at terminal E6. Terminal E6 grounds CKT 1391 (LT GRN). The coil of the LH front door lock isolation relay energizes. This opens the normally-closed relay contacts. This action disables the door lock circuit to the following components:

    • Right front door lock
    • Rear door locks
    • Fuel door release solenoid (Pontiac only)

Simultaneously, the MALL module provides battery voltage on CKT 694 (TAN) to the left front door lock actuator while holding CKT 295 (GRY) at ground. The left front door unlocks.

When the UNLOCK button is pressed a second time (within 5 seconds of the first press), the RFA module turns off the output at terminal E6. This produces the following effects:

    • Removes the ground from CKT 1391 (LT GRN)
    • De-energizes the isolation relay

The relay contacts close. This connects CKT 694 (TAN) to CKT 294 (TAN). This action provides battery voltage to the rest of the door lock actuators. Also, this action provides battery voltage to the fuel door release solenoid on CKT 294 (TAN) while CKT 295 (GRY) is still held at ground (Pontiac only). The rest of the doors unlock. Also, the fuel door unlocks (Pontiac only).

The door lock actuators are usually powered for just a moment. If the actuators remain on, an electronic circuit breaker in each actuator opens in order to protect against damage. Each circuit breaker has a positive temperature coefficient which resets automatically when voltage is removed from the actuator.

Door Lock/Unlock Input Circuits

In order to initiate door locking or unlocking, the MALL module receives an input signal at the following 2 terminals on connector C2:

    • Terminal C6
    • Terminal C7

The following circuits are common to both the keyless entry system and the switches on the front doors:

    • CKT 781 (ORN/BLK)
    • CKT 195 (LT BLU)

Unlock Input Circuit

Pressing a front power door lock switch to the UNLOCK position connects CKT 781 (ORN/BLK) through the switch to ground CKT 1250. CKT 781 (ORN/BLK) grounds the MALL module connector C2 terminal C6 in order to provide the door unlock input signal.

Pressing the door unlock button on the keyless entry transmitter causes the RFA module to ground terminal E5. With this action the RFA module grounds CKT 781 (ORN/BLK). In turn, CKT 781 (ORN/BLK) grounds the MALL module connector C2 terminal C6 in order to provide the door unlock input signal.

Lock Input Circuit

Pressing a front power door lock switch to the LOCK position connects CKT 780 (RED/BLK) through the switch to ground CKT 1250. CKT 780 (RED/BLK) grounds the RFA module at terminal E13 in order to provide the door lock input signal to the RFA module. The RFA module in turn grounds the control signal at terminal E4. This pulls CKT 195 (LT BLU) to ground. This action grounds the MALL module connector C2 terminal C7 in order to provide the door lock input signal. CKT 195 (LT BLU) is also the input circuit for the keyless entry unlock function. Pressing the door lock button on the keyless entry transmitter causes the RFA module to ground terminal E4. With this action the RFA module grounds CKT 195 (LT BLU). In turn, this grounds the MALL module connector C2 terminal C7 in order to provide the door lock input signal.