The body control module (BCM) provides battery positive voltage and ground to the appropriate lock and unlock control circuits of the door lock and unlock relays. The lock control circuits of the driver and passenger door latch assemblies share a common relay; however, the unlock control circuits have separate relays. The system is designed this way so that the keyless entry transmitter may be used to unlock only the driver door.

The BCM supplies and monitors a reference voltage to the door lock/window switch through the door lock switch lock and unlock signal circuits. The door lock/window switch also receives a constant ground source. If a door lock switch is placed in the lock position or unlock position, the reference voltage is taken directly to ground and the BCM detects the voltage drop on the signal circuit.

The BCM, upon receipt of a lock switch lock signal, will switch the all lock relay control circuit to battery positive voltage. This will energize the relay. The relay will supply voltage to the door lock actuator lock control circuits to one side of the lock actuator. Since the opposing side of the lock actuators are connected to ground through the other lock actuator control circuit and the normally closed contacts of the lock or unlock relay, the doors will then lock appropriately. The remaining unlock relays receive voltage from the I/P fuse block, the BCM upon receipt of a unlock signal or driver door unlock signal will switch the appropriate unlock relay to ground. This will energize the appropriate unlock relay. The relay will supply voltage to the appropriate door unlock control circuits to one side of the lock actuator. Since the opposing side of the lock actuators are connected to ground through the other lock actuator control circuits and the normally closed contact of the lock relay, the doors will then unlock appropriately.

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

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the scan tool Central Door Lock Switch and Central Door Unlock Switch parameters while using the door lock switch. The parameter should change between Inactive and Active.

⇒	If the value does not change between commanded states, refer to Door Lock Switch Malfunction

2. Command the driver door and passenger door latches to LOCK and UNLOCK by using the door lock switch. The doors should perform the LOCK and UNLOCK function.

⇒	If the driver door does not UNLOCK, refer to Driver Door Unlock Relay Malfunction.

⇒	If the passenger door do not UNLOCK, refer to Door Unlock Relay Malfunction

⇒	If one or both doors do not LOCK, refer to Door Lock Relay Malfunction

Door Lock Switch Malfunction

1. Ignition OFF, disconnect the X2 harness connector at the door lock/window switch.
2. Test for less than 1 Ω between the ground circuit terminal 4 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify the scan tool Central Door Lock Switch parameter is Inactive.

⇒	If not the specified value, test the signal circuit terminal 15 for a short to ground. If the circuit tests normal, replace the BCM.

4. Verify the scan tool Central Door Unlock Switch parameter is Inactive.

⇒	If not the specified value, test the signal circuit terminal 5 for a short to ground. If the circuit tests normal, replace the BCM

5. Install a 3A fused jumper wire between the signal circuit terminal 5 and ground. Verify the scan tool Central Door Unlock Switch parameter is Active.

⇒	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 BCM.

6. Install a 3A fused jumper wire between the signal circuit terminal 15 and ground. Verify the scan tool Central Door Lock Switch parameter is Active.

⇒	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 BCM.

7. If all circuits test normal, test or replace the door lock/window switch.

Driver Door Unlock Relay Malfunction

1. Ignition OFF, disconnect the DRIVER UNLOCK relay.
2. Test for less than 1 Ω between the 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 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 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.

5. Verify that a test lamp illuminates between the 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 control circuit terminal 85 and the B+ circuit terminal 86.
7. Command the Driver Door Unlock/Lock with a scan tool. The test lamp should briefly illuminate during the UNLOCK command.

⇒	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. Ignition OFF, connect the DRIVER UNLOCK relay and disconnect the harness connector at the right front door latch.
9. Test for less than 5 Ω between the control circuit terminal 7 and ground.

⇒	If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the DRIVER UNLOCK relay.

10. Connect a test lamp between the control circuit terminal 7 and ground.
11. Ignition ON, command the right front door latch to UNLOCK by using the door lock switch. The test lamp should briefly illuminate when commanding the UNLOCK state.

⇒	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 DRIVER UNLOCK relay.

12. If all circuits test normal, test or replace the right front door latch.

Door Unlock Relay Malfunction

1. Ignition OFF, disconnect the PASS UNLOCK relay.
2. Test for less than 1 Ω between the 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 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 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.

5. Verify that a test lamp illuminates between the 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 control circuit terminal 85 and the B+ circuit terminal 86.
7. Ignition ON, command the All Doors Unlock/Lock with a scan tool. The test lamp should briefly illuminate during the UNLOCK command.

⇒	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. Ignition OFF, connect the PASS UNLOCK relay and disconnect the harness connector at the left front door latch.
9. Test for less than 5 Ω between the control circuit terminal 2 and ground.

⇒	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 PASS UNLOCK relay.

10. Ignition ON, connect a test lamp between the control circuit terminal 2 and ground.
11. Ignition ON, command the All Doors Unlock/Lock with a scan tool. The test lamp should briefly illuminate when commanding the UNLOCK state.

⇒	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 PASS UNLOCK relay.

12. If all circuits test normal, test or replace the left front door latch.

Door Lock Relay Malfunction

1. Ignition OFF, disconnect the ALL LOCK relay.
2. Test for less than 1 Ω between the 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 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 B+ circuit terminal 87 and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

5. Connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 85.
6. Command the All Doors Unlock/Lock with a scan tool. The test lamp should illuminate during the LOCK command.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground 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 voltage. If the circuit tests normal, replace the BCM.

7. Ignition OFF, connect the ALL LOCK relay and disconnect the harness connector at the appropriate door latch.
8. Test for less than 5 Ω between the control circuit terminal listed below and ground:

•	Right front door latch terminal 8.

•	Left front door latch terminal 3.

⇒	If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test or replace the ALL LOCK relay.

9. Ignition ON, connect a test lamp between the control circuit terminal listed below and ground:

•	Right front door latch terminal 8.

•	Left front door latch terminal 3.

10. Ignition ON, command the door latch to LOCK by using the door lock switch. The test lamp should briefly illuminate during the LOCK command.

⇒	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 ALL LOCK relay.

11. If all circuits test normal, test or replace the door latch.

Door Lock Window/Switch Test

1. Ignition OFF, disconnect the X2 harness connector at the door lock/window switch.
2. Test for infinite resistance between the signal terminals 5 and 15 and the ground terminal 4 with the switch in the open position.

⇒	If less than the specified value, replace the door lock/window switch.

3. Test for less than 2 Ω between the signal terminal 15 and the ground terminal 4 with the switch in the lock position.

⇒	If greater than the specified range, replace the door lock/window switch.

4. Test for less than 2 Ω between the signal terminal 5 and the ground terminal 4 with the switch in the unlock position.

⇒	If greater than the specified range, replace the door lock/window switch.

Door Latch Test

1. Ignition OFF, disconnect the harness connector at the appropriate door latch.
2. Install a 25A 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

⇒	If it does not perform as specified, replace the door latch.

Relay Test

1. Ignition OFF, disconnect the appropriate relay.
2. Test for 60-200 Ω 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 relay.

4. Test for less than 2 Ω between terminals 30 and 87A.

⇒	If greater than the specified range, replace the relay.

5. Install a 3A fused jumper wire between relay terminal 85 and 12V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 Ω between terminals 30 and 87.

⇒	If greater than specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.