GM Service Manual Online
For 1990-2009 cars only

Diagnostic Fault Information

Perform the Control Module References prior to using this diagnostic procedure.

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Driver Door Lock Switch Lock Signal

B3150 02

3

3

--

Driver Door Lock Switch Unlock Signal

B3140 02

3

3

--

Passenger Door Lock Switch Lock Signal

B3150 02

4

4

--

Passenger Door Lock Switch Unlock Signal

B3140 02

4

4

--

Driver Door Lock Actuator Unlock Control

3

3

3

--

Door Latch Motor Control

1

1

1

--

Door Unlatch Motor Control

1

1

1

--

Front Passenger Door Lock Actuator Unlock Control

3

3

3

--

LR Door Lock Actuator Lock Control

2

2

2

--

LR Door Lock Actuator Unlock Control

2, 3

2, 3

2, 3

--

RR Door Lock Actuator Lock Control

2

2

2

--

RR Door Lock Actuator Unlock Control

2, 3

2, 3

2, 3

--

Driver Door Switch Assembly Ground

--

3

--

--

Passenger Door Lock Switch Ground

--

4

--

--

1. Power Door Latch System Malfunction

2. Rear Power Door Lock Malfunction

3. Driver Door Lock Switch Malfunction

4. Passenger Door Lock Switch Malfunction

Circuit/System Description

The driver door lock switch is wired to the driver door switch. The lock switch receives a constant ground source. There are 2 signal circuits, one for lock signal, and one for unlock signal. When the switch is activated for a lock or unlock function, the normally open switch contacts for that function are closed and provide a switched ground signal to the driver door switch. These switch activations are detected and processed by the driver door switch and then communicated to the driver door module (DDM) via a serial data message.

The front doors do not have traditional door lock actuators. They have electronically controlled door latches that will operate depending on the status of the door lock system. This status is determined by the front door modules and the last known state of the lock system. If the last known state is LOCK, the latches will not release when the door handles are operated. If the last known state is UNLOCK, the latches will release when the door handles are operated. The front doors are also equipped with red door lock status indicators. The front door modules will supply power and ground to the indicators to illuminate them when the lock system is in a virtual state of lock. The indicators will not continuously illuminate when the vehicle is locked. They will illuminate for approximately 5 seconds after a lock switch activation or after a door handle has been operated and the front door modules are in a virtual state of lock.

Reference Information

Schematic Reference

Door Lock/Indicator Schematics

Connector End View Reference

Power Door Systems Connector End Views

Description and Operation

Power Door Locks Description and Operation

Electrical Information Reference

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

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Circuit/System Verification

  1. Ignition ON, observe the scan tool Door Lock Switch parameter while using the driver door lock switch. The parameter should change from Idle to Lock and Unlock.
  2. If the parameter does not change, refer to Driver Door Lock Switch Malfunction.
  3. Command the doors to LOCK and UNLOCK by using the driver and passenger door lock switches, the each door should perform the LOCK and UNLOCK command from each switch.
  4. If the driver door lock is inoperative, refer to Driver Door Lock Malfunction.
  5. Observe the scan tool Driver Door Handle parameter while using the driver door handle, the parameter should change from Inactive to Active.
  6. If the parameter does not change, refer to Driver Door Handle Switch Malfunction.

Circuit/System Testing

Driver Door Lock Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the driver door lock switch.
  2. Test for less than 10 ohms between the ground circuit terminal C 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 Idle.
  5. If not the specified value, test the signal circuit terminal listed below for a short to ground.
    • Signal circuit terminal D
    • Signal circuit terminal E
  6. Connect a 5A fused jumper wire between the signal circuit terminal D and ground, verify the scan tool Door Lock Switch parameter is Lock.
  7. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the driver door switch assembly.
  8. Connect a 5A fused jumper wire between the signal circuit terminal E and ground, verify the scan tool Door Lock Switch parameter is Unlock.
  9. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the driver door switch assembly.
  10. 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 latch.
  2. Test for less than 5 ohms between the control circuit terminal listed below and ground.
  3. • Control circuit terminal 3
    • Control circuit terminal 4
    If greater than specified value, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the DDM.
  4. Connect a test lamp between the control circuit terminal 3 and control circuit terminal 4.
  5. Ignition ON, command the driver door latch to LOCK and UNLOCK by using the driver door lock switch, the test lamp should briefly illuminate during the LOCK and UNLOCK command.
  6. If the test lamp does not illuminate during either of the commands, test either control circuit for a short to ground. If both circuits tests normal, replace the DDM.
  7. If all circuits test normal, test or replace the driver door latch.

Driver Door Handle Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the LF door handle switch assembly.
  2. Test for less than 10 ohms between the ground circuit terminal 3 and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Test for less than 10 ohms between the ground circuit terminal 6 and ground.
  5. If greater than the specified range, test the ground circuit for an open/high resistance.
  6. Ignition ON, verify the scan tool Driver Door Handle parameter is Inactive.
  7. If not the specified value, test the signal circuit terminal listed below for a short to ground. If the circuits tests normal, replace the DDM.
    • Signal circuit terminal 4
    • Signal circuit terminal 5
  8. Ignition ON, connect a 5A fused jumper wire between the signal circuit terminal listed below and ground. Verify the scan tool Driver Door Handle parameter is Active
  9. • Signal circuit terminal 4
    • Signal circuit terminal 5
    If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuits tests normal, replace the DDM.
  10. If all circuits test normal, test or replace the LF door handle switch assembly.

Component Testing

  1. Ignition OFF, disconnect the harness connector at the driver door latch.
  2. Ignition ON, install a 15A fused jumper wire between the control terminal 3 and 12 volts.
  3. Momentarily install a jumper wire between the control terminal 4 and ground. The door latch should perform the LOCK/UNLOCK function.
  4. If the function does not perform as specified, replace the door latch.
  5. Reverse the jumper wires, the door latch assembly should perform the UNLOCK/LOCK function.
  6. If the function does not perform as specified, replace the driver door latch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Front Side Door Outside Handle Replacement
    •  Front Side Door Lock and Inside Handle Rod Replacement
    •  Control Module References for DDM replacement, setup, and programming