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 switch through the door lock switch lock/unlock signal circuit. The door lock switch also receives a constant ground source. If a door lock switch is placed in the lock position or unlock position, 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 lock 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 appropriate 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 Driver Door Lock Sw, Psgr Door Lock Sw, Driver Door Unlock Sw and Psgr Door Unlock Sw parameters while using the door lock switches. The parameter should change between Inactive and Active.

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

2. Command the door latches to LOCK and UNLOCK with the scan tool, the doors should perform LOCK and UNLOCK functions.

⇒	If a door latch does not LOCK or UNOCK, refer to Door Lock Malfunction.

Door Lock Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate door lock switch.
2. Test for less than 1 ohm between the ground circuit terminal 3 and ground.

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

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

⇒	If not the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the BCM.

4. Verify the scan tool Door Unlock Sw parameter is Inactive.

⇒	If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the BCM.

5. Install a 3 amp fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool Door Lock Sw 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 3 amp fused jumper wire between the signal circuit terminal 2 and ground. Verify the scan tool Door Unlock Sw 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 switch.

Door Lock Malfunction

1. Ignition OFF, disconnect the X1 harness connector at the I/P fuse block.
2. Test for less than 1 ohm between the ground circuit terminal 25 and ground.

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

3. Connect the X1 harness connector at the I/P fuse block.
4. Ignition ON, verify that a test lamp illuminates between the DR/LCK fuse test point and and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit terminal 3 for a short to ground or an open/high resistance.

5. Igniton OFF, disconnect the X3 harness connector at the the I/P fuse block.
6. Connect a test lamp between the control circuit terminal 42 and ground.
7. Ignition ON, command the Lock Rear Doors 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 ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.

⇒	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.

8. Connect a test lamp between the control circuit terminal 41 and B+.
9. Command the Unlock Rear Doors 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 ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.

⇒	If the test lamp is always OFF, test the control circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.

10. Connect a test lamp between the control circuit terminal 8 and B+.
11. Command the Driver Door 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 ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.

⇒	If the test lamp is always OFF, test the control circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.

12. Ignition OFF, connect the X3 harness connector at the I/P fuse block and disconnect the harness connector at the appropriate door latch.
13. Test for less than 1 ohm between the control circuit terminal and ground for the door latch listed below:

•	Driver door latch control circuit terminal 2

•	Driver door latch control circuit terminal 3

•	Left rear door latch control circuit terminal 1

•	Left rear door latch control circuit terminal 2

•	Right rear door latch control circuit terminal 5

•	Right rear door latch control circuit terminal 6

•	Passenger door latch control circuit terminal 5

•	Passenger door latch control circuit terminal 6

⇒	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 I/P fuse block.

14. Connect a test lamp between control circuit terminals for the door latch listed below:

•	Driver door latch control circuit terminal 2 and control circuit terminal 3

•	Left rear door latch control circuit terminal 1 and control circuit terminal 2

•	Right rear door latch control circuit terminal 5 and control circuit terminal 6

•	Front passenger door latch control circuit terminal 5 and control circuit terminal 6

15. Ignition ON, command the door latch to LOCK and UNLOCK with a scan tool. The test lamp should illuminate when commanding the LOCK and UNLOCK states.

⇒	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 I/P fuse block.

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

Door Lock Switch Test

1. Ignition OFF, disconnect the harness connector at the appropriate door lock switch.
2. Test for infinite resistance between the signal terminals 2 and 1 and the ground terminal 3 with the switch in the open position.

⇒	If not the specified value, replace the door lock switch.

3. Test for less than 2 ohms between the signal terminal 1 and the ground terminal 3 with the switch in the LOCK position.

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

4. Test for less than 2 ohms between the signal terminal 2 and the ground terminal 3 with the switch in the UNLOCK position.

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

Door Latch

1. Ignition OFF, disconnect the harness connector at the appropriate door latch.
2. Install a 15A fused jumper wire between the lock control terminal listed below and 12 volts:

•	Driver door latch control terminal 2

•	Left rear door latch control terminal 2

•	Passenger door control terminal 5

•	Right rear door control terminal 5

3. Momentarily install a jumper wire between the unlock control terminal listed below and ground. The door latch should perform the LOCK/UNLOCK function.

•	Driver door latch control terminal 3

•	Left rear door latch control terminal 1

•	Passenger door latch control terminal 6

•	Right rear door latch control terminal 6

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

4. Reverse the jumper wires. The door latch should perform the UNLOCK/LOCK function.
5. If the function does not perform as specified, replace the door latch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.