GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2008 🢒 Grand Prix 🢒 Body Systems 🢒 Vehicle Access 🢒 Power Door Locks Inoperative

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

BCM B+

1

1

--

--

Driver Door Lock Switch Unlock Signal

2

2

2

--

Driver Door Lock Switch Lock Signal

2

2

2

--

Passenger Door Lock Switch Unlock Signal

2

2

2

--

Passenger Door Lock Switch Lock Signal

2

2

2

--

Driver Door Lock Actuator Unlock Control

1

1

1

--

Door Lock Actuator Unlock Control

1

1

1

--

Door Lock Actuator Lock Control

1

1

1

--

Door Lock Switch Ground

--

2

2

--

BCM Ground

--

1

1

--

1. Door Lock Malfunction

2. Door Lock Switch Malfunction

Circuit/System Description

When the body control module (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 door lock actuator lock control circuit is at ground potential within the BCM, the door lock actuators transitions to the LOCK position and 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 circuit to voltage. Since the door lock actuator unlock control circuit is at ground potential within the BCM, the door lock actuators 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 motor. 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.

Reference Information

Schematic Reference

Door Lock/Indicator Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Power Door Locks Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Ignition ON, observe the scan tool RF Door Lock Switch and RF Door Unlock Switch parameters while using the passenger door lock switch. The parameter should change between Active and Inactive.
    2. ⇒If the value does not change, refer to Passenger Door Lock Switch Malfunction.
  2. Command all doors LOCK and UNLOCK by using the driver door lock switch. All doors should perform the LOCK and UNLOCK function.
    3. ⇒If the doors do not LOCK/UNLOCK refer to Driver Door Lock Switch Malfunction.
  3. Command all doors to LOCK and UNLOCK with a scan tool. All doors should perform the LOCK and UNLOCK function.
    4. ⇒If the driver door does not LOCK or UNLOCK, refer to Driver Door Lock Malfunction.
    ⇒If one or more vehicle doors do not LOCK or UNLOCK, refer to Door Lock Malfunction.

Circuit/System Testing

Passenger Door Lock Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the front passenger door lock switch.
  2. Test for less than 1 ohm between the ground circuit terminal A and ground.
    3. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, test for greater than 10 volts between the signal circuit terminal F and ground.
    4. ⇒If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  4. Observe the scan tool RF Door Lock Switch parameter while installing a 3A fused jumper wire between the signal circuit terminal F and ground. The parameter should change from Inactive to Active.
    5. ⇒If the parameter does not change, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
  5. Test for greater than 10 volts between the signal circuit terminal G and ground.
    6. ⇒If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  6. Observe the scan tool RF Door Unlock Switch parameter while installing a 3A fused jumper wire between the signal circuit terminal G and ground. The parameter should change from Inactive to Active.
    7. ⇒If the parameter does not change, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
  7. If all circuits test normal, test or replace the passenger door lock switch.

Driver Door Lock Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the driver door lock switch.
  2. Test for less than 1 ohm between the ground circuit terminal A and ground.
    3. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, test for greater than 10 volts between the signal circuit terminal F and ground.
    4. ⇒If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  4. Observe the function of the door locks while installing a 3A fused jumper wire between the signal circuit terminal F and ground. The doors should perform the LOCK function.
    5. ⇒If the doors do not LOCK, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
  5. Test for greater than 10 volts between the signal circuit terminal G and ground.
    6. ⇒If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  6. Observe the function of the door locks while installing a 3A fused jumper wire between the signal circuit terminal G and ground. The doors should perform the UNLOCK function.
    7. ⇒If the doors do not UNLOCK, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
  7. If all circuits test normal, test or replace the driver door lock switch.

Driver Door Lock Malfunction

  1. Ignition OFF, disconnect the harness connector at the driver door lock.
  2. Ignition ON, connect a test lamp between control circuit terminal 3 and control circuit terminal 2.
  3. Command the driver door to LOCK and UNLOCK with a scan tool. The test lamp should illuminate when changing between the commanded states.
    4. ⇒If the test lamp is always OFF, during either of the commands, test either control circuit for a short to ground. If the circuits test normal, replace the BCM.
    ⇒If the test lamp is always ON, test either control circuit for a short to voltage. If the circuits test normal, replace the BCM.
  4. If all circuits test normal, test or replace the driver door lock.

Door Lock Malfunction

  1. Ignition OFF, disconnect the X2 harness connector at the BCM.
  2. Test for less than 1 ohm between the ground circuit terminal 50 and ground.
    3. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 49 and ground.
    4. ⇒If the test lamp does not illuminate, test the B+ circuit for a short to ground or open/high resistance.
  4. Ignition OFF, connect the harness connector at the BCM and disconnect the harness connector at the appropriate passenger door lock.
  5. Ignition ON, connect a test lamp between the control circuit terminals of the door lock listed below.
    6. • Front passenger door lock terminals 5 and 6
    • LR passenger door lock terminals 2 and 3
    • RR passenger door lock terminals 5 and 6
  6. Command all doors to LOCK and UNLOCK with a scan tool. The test lamp should illuminate when changing between the commanded states.
    7. ⇒If the test lamp is always OFF during either of the commands, test either control circuit for a short to ground. If the circuits test normal, replace the BCM.
    ⇒If the test lamp is always ON, test either control circuit for a short to voltage. If the circuits test normal, replace the BCM.
  7. If all circuits test normal, test or replace the passenger door lock.

Component Testing

Door Lock Switch

  1. Ignition OFF, disconnect the harness connector at the appropriate door lock switch.
  2. Test for infinite resistance between the signal terminal G and F and the ground terminal A with the switch in the open position.
    3. ⇒If not the specified value, replace the door lock switch.
  3. Test for less than 2 ohms between the signal terminal G and the ground terminal A with the switch in the UNLOCK position.
    4. ⇒If greater than the specified range, replace the door lock switch.
  4. Test for less than 2 ohms between the signal terminal F and the ground terminal A with the switch in the UNLOCK position.
    5. ⇒If greater than the specified range, replace the door lock switch.

Door Lock

  1. Ignition OFF, disconnect the harness connector at the appropriate door lock.
  2. Install a 15-amp fused jumper wire between the lock control terminal listed below and 12 volts.
    3. • Front passenger door lock terminal 5
    • LR passenger door lock terminal 2
    • RR passenger door lock terminal 5
    • Driver door lock terminal 2
  3. Momentarily install a jumper wire between the unlock control terminal listed below and ground. The door lock should perform the LOCK/ UNLOCK function
    4. • Front passenger door lock terminal 6
    • LR passenger door lock terminal 3
    • RR passenger door lock terminal 6
    • Driver door lock terminal 3
    ⇒If the function does not perform as specified, replace the door lock.
  4. Reverse the jumper wires; the door lock should perform the UNLOCK/LOCK function.
  5. If the function does not perform as specified, replace the door lock.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Rear Door Lock Replacement
    •  Front Side Door Lock Replacement
    •  Control Module References for BCM replacement, setup, and programming