Power Door Locks Malfunction (With RPO AXC/AXE)
Power Door Locks Malfunction (With RPO AXC/AXE)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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/System Description
The driver and front passenger power door lock switches are integral components of the driver door module (DDM) and passenger door module (PDM). 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 GMLAN 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 DDM and PDM 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. The BCM is responsible for controlling the left and right rear passenger door lock motors. The BCM, upon receipt of a lock or unlock serial data signal, will control either the rear door lock or unlock relay. When the appropriate door lock relay is energized, the rear power door lock motors will lock or unlock the rear doors.
Circuit/System Verification
1. Ignition ON, observe the scan tool Door Lock Actuator Cmd parameter while using the door lock switch on the DDM and PDM. The reading should change between Off, Unlock or Lock.
^ If the reading does not change, replace the appropriate door module.
2. Command the doors to LOCK and UNLOCK with the scan tool, each door should LOCK and UNLOCK while changing between the commanded states.
^ 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
^ If a rear door does not UNLOCK, refer to Door Unlock Relay Malfunction
^ If a rear door does not LOCK, refer to Door Lock Relay Malfunction.
Circuit/System Testing
Driver Door Lock Malfunction
1. Ignition OFF, disconnect the harness connector X1 at the DDM.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 4 and ground.
^ If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the DR/LCK fuse is open, replace the DDM.
3. Ignition OFF, reconnect the DDM and disconnect the harness connector at the driver door latch assembly.
4. Ignition OFF, test for less than 2.0 ohms between the lock control circuit terminal 3 and ground.
^ If greater than the specified range, test the lock control circuit for a short to voltage or an open/high resistance. If circuits test normal, replace the DDM.
5. Ignition OFF, test for less than 2.0 ohms between the unlock control circuit terminal 2 and ground.
^ If greater than the specified range, test the unlock control circuit for a short to voltage or an open/high resistance. If circuits test normal, replace the DDM.
6. Ignition ON, connect a test lamp between the lock control circuit terminal 3 and unlock control circuit terminal 2.
7. Command the door to LOCK/UNLOCK with a scan tool. The test lamp should briefly illuminate when commanding the LOCK and UNLOCK states.
^ If the test lamp is always OFF during either of the commands, test for a short to ground on either control circuit. If the circuits test normal, replace the DDM.
8. If the circuits test normal, test or replace the driver door latch assembly.
Passenger Door Lock Malfunction
1. Ignition OFF, disconnect the harness connector X1 at the PDM.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 4 and ground.
^ If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the PDM fuse is open, replace the PDM.
3. Ignition OFF, reconnect the PDM and disconnect the harness connector at the passenger door latch assembly.
4. Ignition OFF, test for less than 2.0 ohms between the lock control circuit terminal 3 and ground.
^ If greater than the specified range, test the lock control circuit for a short to voltage or an open/high resistance. If circuits test normal, replace the PDM.
5. Ignition OFF, test for less than 2.0 ohms between the unlock control circuit terminal 2 and ground.
^ If greater than the specified range, test the unlock control circuit for a short to voltage or an open/high resistance. If circuits test normal, replace the PDM.
6. Ignition ON, connect a test lamp between the lock control circuit terminal 3 and unlock control circuit terminal 2.
7. Command the door to LOCK/UNLOCK with a scan tool. The test lamp should briefly illuminate when commanding the LOCK and UNLOCK states.
^ If the test lamp remains OFF during either of the commands, test for a short to ground on either control circuit. If the circuits test normal, replace the PDM.
8. If the circuits test normal, test or replace the passenger door latch assembly.
Door Unlock Relay Malfunction
1. Ignition OFF, disconnect the UNLCK relay.
2. Test for less than 1.0 ohm between the switch side ground circuit terminal 87A and ground.
^ If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp does not illuminate between the switch side control circuit terminal 30 and ground.
^ If the test lamp illuminates, test the control circuit for a short to voltage.
4. Verify that a test lamp illuminates between the coil side B+ circuit terminal 86 and ground.
^ If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the DR/LCK fuse is open, test the switch side control circuit terminal 30 for a short to ground. If the circuit tests normal, test or replace the UNLCK relay.
5. Verify that a test lamp illuminates between the switch side B+ circuit terminal 87 and ground.
^ If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
6. Connect a test lamp between the coil control circuit terminal 85 and the coil side B+ circuit terminal 86.
7. Command the rear doors unlock ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
^ If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
^ If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.
8. Install the UNLCK relay.
9. Ignition OFF, disconnect the harness connector at the appropriate door latch.
10. Ignition OFF, test for less than 5 ohms between the control circuit terminal of the appropriate door lock listed below and ground:
* LR door lock terminal 2
* RR door lock terminal 5
^ If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuits test normal, replace the UNLCK relay.
11. Ignition ON, connect a test lamp between the control circuit terminals of the appropriate door lock listed below:
* LR door lock terminals 2 and 3
* RR door lock terminals 5 and 6
12. Ignition ON, command the door latch to LOCK and UNLOCK with a scan tool. The test lamp should turn ON when commanding the LOCK and UNLOCK states.
^ If the test lamp is always OFF, test the control circuit for a short to ground. If the circuit tests normal, test or replace the UNLCK relay.
13. If all circuits test normal, test or replace the appropriate door latch.
Door Lock Relay Malfunction
1. Ignition OFF, disconnect the LCK relay.
2. Test for less than 1.0 ohm between the switch side ground circuit terminal 87A and ground.
^ If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp does not illuminate between the switch side control circuit terminal 30 and ground.
^ If the test lamp illuminates, test the control circuit for a short to voltage.
4. Verify that a test lamp illuminates between the coil side B+ circuit terminal 86 and ground.
^ If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the DR/LCK fuse is open, test the switch side control circuit terminal 30 for a short to ground. If the circuit tests normal, test or replace the LCK relay
5. Verify that a test lamp illuminates between the switch side B+ circuit terminal 87 and ground.
^ If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
6. Connect a test lamp between the coil control circuit terminal 85 and the coil side B+ circuit terminal 86.
7. Command the rear doors unlock ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
^ If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
^ If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.
8. Install the LCK relay.
9. Ignition OFF, disconnect the harness connector at the appropriate door latch.
10. Ignition OFF, test for less than 5 ohms between the control circuit terminal of the appropriate door lock listed below and ground:
* LR door lock terminal 3
* RR door lock terminal 6
^ If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuits test normal, replace the LCK relay.
11. Ignition ON, connect a test lamp between the control circuit terminals of the appropriate door lock listed below:
* LR door lock terminals 2 and 3
* RR door lock terminals 5 and 6
12. Ignition ON, command the door latch to LOCK and UNLOCK with a scan tool. The test lamp should turn ON when commanding the LOCK and UNLOCK states.
^ If the test lamp is always OFF, test the control circuit for a short to ground. If the circuit tests normal, test or replace the LCK relay.
13. If all circuits test normal, test or replace the appropriate door latch.
Component Testing
Door Latch Assembly
1. Install a 25-amp fused jumper wire between the lock control terminal and 12 volts. Momentarily install a jumper wire between the unlock control terminal and ground. The appropriate door lock should perform the LOCK/ UNLOCK function.
^ If the function does not perform as specified, replace the appropriate door lock.
2. Reverse the jumper wires; the appropriate door lock should perform the UNLOCK/LOCK function.
^ If the function does not perform as specified, replace the appropriate door lock.
Relay Test
1. Ignition OFF, disconnect the applicable relay.
2. Test for 60-200 ohms between terminals 85 and 86.
^ If not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals:
* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87
^ If less than the specified value, replace the applicable relay.
4. Test for less than 2 ohms of resistance between terminals 30 and 87A.
^ If greater than the specified range, replace the relay.
5. Install a 3-amp fused jumper wire between applicable relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Measure for less than 2 ohms between terminals 30 and 87.
^ If greater than specified range, replace the applicable relay.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
* Front Side Door Latch Replacement
* Rear Side Door Latch Replacement
* Relay Replacement (Attached to Wire Harness) Relay Replacement (Within an Electrical Center)