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

I/P Fuse Block B+

3

3

--

--

Driver Door Latch Control

1

1

1

--

Passenger Door Latch Control

2

2

2

--

Doors Locked Control

B3135 00

3

3

--

Doors Unlocked Control

B3130 00

3

3

--

Rear Door Latch Control

3

3

3

--

Endgate Lock Actuator Control

3

3

3

--

I/P Fuse Block Ground

--

3

3

--

1. Driver Door Latch Malfunction

2. Passenger Door Latch Malfunction

3. Rear Door/Liftgate Latch Malfunction

Circuit/System Description

The driver and front passenger power door lock switches are integral components of the driver door switch (DDS) and passenger door switch (PDS). The switches consist of 2 positions, lock and unlock, and are in the normally open state. When placed in either the lock or unlock positions, the switches provide a direct input to there respective door control module. When a power door lock switch is operated to the lock or unlock position, the associated door control module responds by sending a serial data message indicating a change in the switch's position. This serial data message is received by the opposite door control module as well as the body control module (BCM). The DDS and PDS respond to the lock/unlock request by activating their associated power door lock motors to the appropriate direction to lock or unlock the front doors.

Reference Information

Schematic Reference

Door Lock/Indicator Schematics

Connector End View Reference

Vehicle Access 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

    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Verification

Command the doors to LOCK and UNLOCK by using the driver and passenger door lock switches, each door should perform the LOCK and UNLOCK function from each switch.

If the driver door does not LOCK or UNLOCK, refer to Driver Door Lock Malfunction.
If the passenger door does not LOCK or UNLOCK, refer to Passenger Door Lock Malfunction

Circuit/System Testing

Driver Door Lock Malfunction

  1. Ignition OFF, disconnect the harness connector at the driver door latch.
  2. Test for less than 2 ohms between the control circuit terminal 3 and ground.
  3. If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If circuits test normal, replace the DDS.
  4. Test for less than 2 ohms between the control circuit terminal 2 and ground.
  5. If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If circuits test normal, replace the DDS.
  6. Ignition ON, connect a test lamp between the control circuit terminal 3 and control circuit terminal 2.
  7. Command the door to LOCK and UNLOCK with a scan tool. The test lamp should briefly illuminate when commanding the LOCK and UNLOCK states.
  8. 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 DDS.
  9. If the circuits test normal, test or replace the driver door latch.

Passenger Door Lock Malfunction

  1. Ignition OFF, disconnect the harness connector at the passenger door latch.
  2. Test for less than 2 ohms between the control circuit terminal 5 and ground.
  3. If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If circuits test normal, replace the PDS.
  4. Test for less than 2 ohms between the control circuit terminal 6 and ground.
  5. If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If circuits test normal, replace the PDS.
  6. Ignition ON, connect a test lamp between the control circuit terminal 5 and control circuit terminal 6.
  7. Command the door to LOCK and UNLOCK with a scan tool. The test lamp should briefly illuminate when commanding the LOCK and UNLOCK states.
  8. If the test lamp remains OFF during either of the commands, test either control circuit for a short to ground. If the circuits test normal, replace the PDS.
  9. If the circuits test normal, test or replace the passenger door latch.

Component Testing

  1. Ignition OFF, disconnect the harness connector at the appropriate door latch.
  2. Install a 15A fused jumper wire between one of the control terminals and 12V. Momentarily install a jumper wire between the other control terminal and ground. Reverse the jumper wires at least two times, the door latch should perform the LOCK/UNLOCK functions.
  3. If it does not perform as specified, replace the door latch

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Front Side Door Lock Replacement
    •  Control Module References for DDS or PDS replacement, programming, and setup