With the headlamp switch in the HEAD position, the headlamp switch headlamp ON signal circuit is grounded through the turn signal/multifunction switch at G201. In response to this input, the body control module (BCM) provides ground to either the headlamp low beam relay control circuit through the headlamp switch signal circuit or the headlamp high beam relay control circuit. The position of the headlamp dimmer switch determines which relay coil has ground. The BCM supplies ground to the relay coil circuits, if the headlamps are necessary. The underhood fuse block supplies battery positive voltage to both relay switch circuits. When the low beam relay coil is energized, current flows through the LH LOW and the RH LOW fuses to the low beam headlamps. When the headlamp high beam relay coil is energized, current flows through the LH HIGH and the RH HIGH fuses to the high beam headlamps. Ground for the left headlamp assembly is provided at G101. Ground for the right headlamp assembly is provided at G102.

Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

Scan Tool Reference

Headlamps Always On - Low Beams

1. Ignition OFF, disconnect the low beam relay.
2. Ignition ON, the low beam headlamps should turn OFF.

⇒	If the low beam headlamps remain illuminated, repair the low beam headlamp voltage supply circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block.

3. Ignition OFF, connect the low beam relay.
4. Disconnect the C2 harness connector at the turn signal/multifunction switch. The low beam headlamps should turn OFF.

⇒	If the low beam headlamps remain illuminated, repair the low beam headlamp relay control circuit for a short to ground. If the circuit tests normal, test or replace the low beam relay.

5. Reconnect the turn signal/multifunction switch C2 harness connector.
6. Disconnect the C1 harness connector at the turn signal/multifunction switch.
7. Connect a 3-amp fused jumper between the headlamp switch headlamps OFF signal circuit and ground.
8. Ignition ON, install a scan tool and observe the Headlamp OFF Switch parameter. The scan tool should display ON.

⇒	If the scan tool indicates the Headlamp OFF Switch parameter is OFF, repair the headlamp switch headlamps off signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

9. With the scan tool, observe the Headlamps ON Switch parameter. The scan tool should display Inactive.

⇒	If the scan tool indicates the Headlamp ON Switch parameter is Active, repair the headlamp switch headlamps on signal circuit for a short to ground. If the circuit tests normal, replace the BCM.

10. Ignition OFF, disconnect the C2 harness connector at the turn signal/multifunction switch.
11. Verify that a test lamp does not illuminate between battery voltage and the headlamp switch signal circuit.

⇒	If the test lamp illuminates, repair the headlamp switch signal circuit for a short to ground. If the circuit tests normal, replace the BCM.

12. If all circuits test normal, test or replace the turn signal/multifunction switch.

Headlamps Always On - High Beams

1. Ignition OFF, disconnect the high beam relay.
2. Ignition ON, the high beam headlamps should turn OFF.

⇒	If the high beam headlamps remain illuminated, repair the high beam headlamp voltage supply circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block.

3. Ignition OFF, connect the high beam relay.
4. Disconnect the BCM C1 harness connector. The high beam headlamps should turn OFF.

⇒	If the high beam headlamps remain illuminated, repair the high beam relay control circuit for a short to ground. If the circuit test normal, test or replace the high beam relay.

5. Connect the BCM C1 harness connector.
6. Disconnect the C2 harness connector at the turn signal/multifunction switch. The high beam headlamps should turn OFF.

⇒	If the high beam headlamps remain illuminated, repair the headlamp dimmer switch high beam signal circuit for a short to ground.

⇒	If the headlamp dimmer switch high beam signal circuit tests normal, repair the flash to pass switch signal circuit for a short to ground. If the circuits test normal, replace the BCM.

7. Verify that a test lamp does not illuminate between battery voltage and the headlamp switch signal circuit.

⇒	If the test lamp illuminates, repair the headlamp switch signal circuit for a short to ground. If the circuit tests normal, replace the BCM.

8. If all circuits test normal, test or replace the turn signal/multifunction switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.