Each door lock switch is wired to the body control module (BCM) through a separate door lock/unlock signal circuit. While these circuits are separated between the BCM and respective door lock switch, they are connected into a single circuit within the BCM. The BCM supplies voltage through the door lock/unlock signal circuits to each door lock switch. When either door lock switch is operated, this supply voltage is pulled to ground, providing the BCM with the required lock or unlock signal. In order for the BCM to distinguish between a lock and unlock signal, the lock switch contains two separate paths for this voltage to flow to the same body ground. When the switch is operated to the unlock position, the supply voltage flows to ground through a 1.5K ohm resistor. When the switch is operated to the lock position, the supply voltage flows to ground through a different part of the switch circuit, which has no resistor. The BCM then interprets the flow of voltage as a lock or unlock request and powers the door lock actuators to the appropriate lock or unlock position.

The BCM powers the reversible door latch assemblies by providing battery positive voltage and ground to the appropriate lock and unlock control circuits of the door latch assemblies. The lock control circuits of the driver and passenger door latch assemblies are all connected together; however, the unlock control circuits are connected in a slightly different way. While the unlock control circuits for the passenger door latch assemblies are connected together, the door latch assembly has a separate unlock control circuit. The system is designed this way so that the keyless entry transmitter may be used to unlock only the driver door. Despite this difference, all lock actuators perform much the same way. When the door latch assemblies are not active, all actuator lock and unlock control circuits are at ground potential within the BCM. Transitioning of the lock actuators to the lock or unlocked position depends upon which control circuits receive voltage and which control circuits receive ground.

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 Door Lock Switch parameters while using the driver and passenger door lock switches. The parameter should change from Idle to Lock and Unlock.

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

2. Command the driver door and passenger door lock actuators to LOCK and UNLOCK with a scan tool, the doors should perform the LOCK and UNLOCK function.

⇒	If one or more vehicle doors do not LOCK or UNLOCK, refer to Door Lock Malfunction.

Door Lock Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the driver door lock switch and passenger door lock switch.
2. Test for less than 30 ohms between the ground circuit terminal A 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 Switch parameter is Idle.

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

4. Install a 3-amp fused jumper wire between the signal circuit terminal C and ground. Verify the scan tool Door Lock Switch parameter is Lock.

⇒	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.

5. Igniton OFF, connect the harness connector at the driver door lock switch.
6. 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.

⇒	If the parameter does not change, test or replace the driver door lock switch.

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

Door Lock Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate door latch.
2. Test for less than 20 ohms between the control circuit terminal listed below and ground:

•	Driver door latch control circuit terminal 2

•	Driver door latch control circuit terminal 3

•	Left rear door latch control circuit terminal 2

•	Left rear door latch control circuit terminal 2

•	Passenger door latch control circuit terminal 5

•	Passenger door latch control circuit terminal 6

•	Right rear door latch control circuit terminal 5

•	Right rear 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 the circuit tests normal, replace the BCM.

3. Connect a test lamp between control circuit terminals listed below:

•	Driver door latch control circuit terminals 2 and 3

•	Left rear door latch control circuit terminals 2 and 3

•	Passenger door latch control circuit terminals 5 and 6

•	Right rear door latch control circuit terminals 5 and 6

4. Ignition ON, command the doors to LOCK and UNLOCK with a scan tool. The test lamp should briefly illuminate while 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 BCM.

5. 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 terminal C and the ground terminal A 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 C and the ground terminal A with the switch in the lock position.

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

4. Test for 1.4-1.6k ohms between the signal terminal C and the ground terminal A with the switch in the unlock position.

⇒	If greater or less 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 lock control terminal 2

•	Left rear door latch lock control terminal 2

•	Passenger door lock control terminal 5

•	Right rear door lock 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 unlock control terminal 3

•	Left rear door latch unlock control terminal 3

•	Passenger door latch unlock control terminal 6

•	Right rear door latch unlock control terminal 6

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

4. Reverse the jumper wires. The door latch assembly 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.