Voltage is applied at all times to the low beam headlamp relay from battery voltage. Two different inputs to the body control module (BCM) can turn ON the low beam headlamps. The headlamp switch and the ambient light sensor.

Automatic Headlamps Operation

When the ambient light sensor detects a low light condition, the BCM then applies a ground to the headlamp low beam relay control circuit. This engages the headlamp relay and applies voltage through the headlamp fuses to the low beam headlamps.

Headlamp Switch Operation

When the headlamp switch is placed in the ON position, ground is applied to the BCM through the headlamp switch circuit. The BCM then applies a ground to the headlamp low beam relay control circuit. This engages the headlamp relay and applies voltage through the headlamp fuses to the low beam headlamps.

The ignition is ON. The headlamps must be commanded ON by either the BCM or by the headlamp switch.

The BCM detects a short to voltage on the low beam headlamps relay control circuit while trying to apply a ground to the circuit.

The low beam headlamps are not illuminated.

The BCM clears this code from current when the fault is removed from the system.

Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

Scan Tool Reference

Ignition ON, turn the headlamps ON. The headlamps should illuminate.

1. Ignition OFF, disconnect the C2 low beam harness connector at the BEC.
2. Connect a test lamp between the control circuit terminal 18 and B+.
3. Command the low beams 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 an open/high resistance. If the circuit tests normal, replace the BCM.

4. Ignition OFF, connect the C2 low beams harness connector at the BEC. Disconnect the harness connector at both low beams.
5. Test for less than 1.0 ohm of resistance between the appropriate low beam ground circuit terminal 2 and ground.

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

6. Connect a test lamp between the control circuit terminal 1 and ground.
7. Command the low beams 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 BEC.

⇒	If the test lamp is always OFF and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the BEC.

⇒	If the test lamp is always OFF and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, replace the appropriate head lamp bulb assembly.

8. If all circuits test normal, replace the appropriate head lamp bulb assembly.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.