GM Service Manual Online
For 1990-2009 cars only

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

Door Lock Switch Signal

B3150 00

B3150 00

B3150 00

--

Door Unlock Switch Signal

B3140 00

B3140 00

B3140 00

--

Driver Door Unlock Control

B3125 02

2, 5

2, 5

--

Doors Lock Control

B3135 02

2, 3, 4, 5

2, 3, 4, 5

--

Passenger Doors Unlock Control

B3130 02

2, 3, 4

2, 3, 4

--

Doors Dead Lock Control

B3797 02

2, 3, 4, 5

2, 3, 4, 5

--

Door Lock Switch Ground

--

1

1

--

1. Door Lock Switch Malfunction

2. Driver Door Unlock Circuit Malfunction

3. Door Unlock Circuit Malfunction

4. Door Lock Circuit Malfunction

5. Door Dead Lock Malfunction

Circuit/System Description

The body control module (BCM) controls the door lock, passenger door unlock and driver door unlock circuits. Voltage is applied to the appropriate circuit when the BCM senses a door lock/unlock switch activation or a keyless entry lock or unlock command.

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 Driver Door Lock Switch, Passenger Door Lock Switch, Driver Door Unlock Switch and Passenger Door Unlock Switch parameters while using the door lock switch. The parameter should change between Inactive and Active.
  2. If the value does not change between commanded states, refer to Door Lock Switch Malfunction.
  3. Command the driver door and passenger door lock actuators to Lock and Unlock with the scan tool, the doors should lock and unlock.
  4. If the driver door does not unlock, refer to Driver Door Unlock Circuit Malfunction.
    If one or more passenger doors do not unlock, refer to Door Unlock Circuit Malfunction.
    If one or more vehicle doors do not lock, refer to Door Lock Circuit Malfunction.
  5. Command the door deadbolt actuators to Lock and Unlock with the scan tool, the doors deadbolt actuators should lock and unlock.
  6. If one or more doors do not unlock, refer to Door Deadlock Circuit Malfunction.

Circuit/System Testing

Door Lock Switch Malfunction

  1. Ignition OFF, disconnect the harness connector X1 at the S26 Hazard Warning Switch.
  2. Test for less than 1 Ω between the ground circuit terminal 1 and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify the scan tool Door Lock Switch parameter is Inactive.
  5. If not the specified parameter, test the signal circuit terminal 9 for a short to ground. If the circuit tests normal, replace the K9 Body Control Module (BCM).
  6. Verify the scan tool Door Unlock Switch parameter is Inactive.
  7. If not the specified parameter, test the signal circuit terminal 11 for a short to ground. If the circuit tests normal, replace the K9 Body Control Module (BCM)
  8. Install a 3 A fused jumper wire between the signal circuit terminal 11 and ground. Verify the scan tool Door Unlock Switch parameter is Active.
  9. If not the specified parameter, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module (BCM)
  10. Install a 3 A fused jumper wire between the signal circuit terminal 9 and ground. Verify the scan tool Door Lock Switch parameter is Active.
  11. If not the specified parameter, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module (BCM).
  12. If all circuits test normal, test or replace the S26 Hazard Warning Switch.

Driver Door Unlock Circuit Malfunction

  1. Ignition OFF, disconnect the A23D Door Latch Assembly - Driver.
  2. Connect a test lamp between the driver door unlock control circuit listed and ground.
  3. • Left hand drive A23D Door Latch Assembly - Driver terminal 3
    • Right hand drive A23D Door Latch Assembly - Driver terminal 8
    If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module (BCM).
  4. Test for less than 30 Ω between the driver door unlock and lock control circuit terminals listed.
  5. • Left hand drive A23D Door Latch Assembly - Driver terminal 2 and 3
    • Right hand drive A23D Door Latch Assembly - Driver terminal 7 and 8
    If greater than the specified range, test the driver door unlock and lock circuits for an open/high resistance. If both circuits test normal, replace the K9 Body Control Module (BCM).
  6. If all circuits test normal, test or replace the A23D Door Latch Assembly - Driver.

Door Unlock Circuit Malfunction

  1. Ignition OFF, disconnect the inoperative door latch.
  2. Connect a test lamp between the door unlock control circuit listed and ground.
  3. • Left hand drive A23P Door Latch Assembly - Passenger terminal 8
    • Right hand drive A23P Door Latch Assembly - Passenger terminal 3
    • A23LR Door Latch Assembly - Left Rear terminal 3
    • A23RR Door Latch Assembly - Right Rear terminal 8
    If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module (BCM).
  4. Test for less than 30 Ω between the door unlock and lock control circuit terminals listed.
  5. • Left hand drive A23P Door Latch Assembly - Passenger terminal 7 and 8
    • Right hand drive A23P Door Latch Assembly - Passenger terminal 2 and 3
    • A23LR Door Latch Assembly - Left Rear terminal 2 and 3
    • A23RR Door Latch Assembly - Right Rear terminal 7 and 8
    If greater than the specified range, test the passenger door unlock and lock circuits for an open/high resistance. If both circuits test normal, replace the K9 Body Control Module (BCM).
  6. If all circuits test normal, test or replace the inoperative door latch.

Door Lock Circuit Malfunction

  1. Ignition OFF, disconnect the KR97D Driver Door Lock Relay.
  2. Connect a test lamp between the door deadbolt control circuit terminal 85 and ground.
  3. If the test lamp illuminates, test the control circuit for a short to voltage.
  4. Command the door deadbolt actuators to Lock and Unlock with a scan tool. The test lamp should illuminate briefly when changing between the commanded states.
  5. If the test lamp does not illuminate, test the control circuit for an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module (BCM).
  6. Ignition OFF, disconnect the inoperative door latch.
  7. Connect a test lamp between the door lock control circuit listed and ground.
  8. • Left hand drive A23D Door Latch Assembly - Driver terminal 2
    • Right hand drive A23D Door Latch Assembly - Driver terminal 7
    • Left hand drive A23P Door Latch Assembly - Passenger terminal 7
    • Right hand drive A23P Door Latch Assembly - Passenger terminal 2
    • A23LR Door Latch Assembly - Left Rear terminal 2
    • A23RR Door Latch Assembly - Right Rear terminal 7
    If the test lamp illuminates, test the control circuit for a short to voltage.
  9. If all circuits test normal, test or replace the inoperative door latch.

Door Deadlock Circuit Malfunction

  1. Ignition OFF, disconnect the inoperative door latch.
  2. Connect a test lamp between the door lock control circuit listed and ground.
  3. • Left hand drive A23D Door Latch Assembly - Driver terminal 1
    • Right hand drive A23D Door Latch Assembly - Driver terminal 6
    • Left hand drive A23P Door Latch Assembly - Passenger terminal 6
    • Right hand drive A23P Door Latch Assembly - Passenger terminal 1
    • A23LR Door Latch Assembly - Left Rear terminal 1
    • A23RR Door Latch Assembly - Right Rear terminal 6
    If the test lamp illuminates, test the control circuit for a short to voltage. If both circuits test normal, replace the K9 Body Control Module (BCM).
  4. Test for less than 30 Ω between the door unlock and lock control circuit terminals listed.
  5. • Left hand drive A23D Door Latch Assembly - Driver terminal 2 and 3
    • Right hand drive A23D Door Latch Assembly - Driver terminal 7 and 8
    • Left hand drive A23P Door Latch Assembly - Passenger terminal 7 and 8
    • Right hand drive A23P Door Latch Assembly - Passenger terminal 2 and 3
    • A23LR Door Latch Assembly - Left Rear terminal 2 and 3
    • A23RR Door Latch Assembly - Right Rear terminal 7 and 8
    If greater than the specified range, test the passenger door unlock and lock circuits for an open/high resistance. If both circuits test normal, replace the K9 Body Control Module (BCM).
  6. If all circuits test normal, test or replace the inoperative door latch.

Component Testing

Door Lock Switch Test

  1. Ignition OFF, disconnect the harness connector X1 at the S26 Hazard Warning Switch.
  2. Test for infinite resistance between the signal terminals 9 and 11 and the ground terminal 1with the switch in the open position.
  3. If less than the specified value, replace the S26 Hazard Warning Switch.
  4. Test for less than 2 Ω between the signal terminal 11 and the ground terminal 1 with the switch in the lock position.
  5. If greater than the specified range, replace the S26 Hazard Warning Switch.
  6. Test for less than 2 Ω between the signal terminal 9 and the ground terminal 1 with the switch in the unlock position.
  7. If greater than the specified range, replace the S26 Hazard Warning Switch.

Door Latch Assembly

  1. Ignition OFF, disconnect the harness connector at the appropriate door lock assembly.
  2. Install a 25 A fused jumper wire between the lock control terminal and 12 V. Momentarily install a jumper wire between the unlock control terminal and ground. The door lock should perform the Lock/ Unlock function.
  3. If the function does not perform as specified, replace the door lock.
  4. Reverse the jumper wires; the appropriate door lock should perform the Unlock/Lock function.
  5. If the function does not perform as specified, replace the door lock.

Relay Test

  1. Ignition OFF, disconnect the KR97D Driver Door Lock Relay.
  2. Test for 60-200 Ω between terminals 85 and 86.
  3. If not within the specified range, replace the KR97D Driver Door Lock Relay.
  4. Test for infinite resistance between the following terminals:
  5. • 30 and 86
    • 30 and 87
    • 30 and 85
    • 85 and 87
    If less than the specified value, replace the KR97D Driver Door Lock Relay.
  6. Test for less than 2 Ω between terminals 30 and 87A.
  7. If greater than the specified range, replace the KR97D Driver Door Lock Relay.
  8. Install a 3 A fused jumper wire between the relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 Ω between terminals 30 and 87.
  9. If greater than specified range, replace the KR97D Driver Door Lock Relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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