Exterior Lamps And Lighting: Headlamps

This document contains both the headlamp and the Auto High Beam Control (AHBC) symptom based diagnostics.

HEADLAMP

CONDITION	POSSIBLE CAUSES	CORRECTION
HEADLAMP DOES NOT ILLUMINATE	1. Ineffective or missing bulb.	1. Test and replace headlamp bulb if required.
	2. Ineffective ground circuit.	2. Test and repair open headlamp ground circuit if required.
	3. Ineffective feed circuit.	3. Test and repair open headlamp low beam or high beam feed circuit if required.
	4. Ineffective headlamp switch.	4. Test and replace the headlamp switch if required.
	5. Ineffective BCM inputs or outputs.	5. Use a diagnostic scan tool to test the BCM inputs and outputs. Refer to the appropriate diagnostic information.
HEADLAMP DOES NOT EXTINGUISH	1. Ineffective feed circuit.	1. Test and repair shorted headlamp low beam or high beam feed circuit if required.
	2. Ineffective headlamp switch.	2. Test and replace the headlamp switch if required.
	3. Ineffective BCM inputs or outputs.	3. Use a diagnostic scan tool to test the BCM inputs and outputs. Refer to the appropriate diagnostic information.

AUTO HIGH BEAM CONTROL - DASM EQUIPPED

CONDITION	POSSIBLE CAUSES	CORRECTION
AUTO HIGH BEAM CONTROL SYSTEM IS INOPERATIVE.	1. Feature is not enabled.	1. Enable Auto Low/High using the customer programmable features function located within the radio.
	2. Automatic headlamps are not turned ON .	2. Turn automatic headlamps ON using the control knob of the headlamp switch.
	3. Headlamp high beams are not selected.	3. Turn high beam headlamps ON using the stalk.
	4. Vehicle speed is below 21 kilometers per hour (km/h) (14 miles per hour/mph).	4. Increase vehicle speed. This system designed to operate at speeds at or above 24 km/h (16 mph).
	5. Incorrect BCM configuration.	5. Use a diagnostic scan tool to check and correct the BCM configuration settings if required. Refer to the appropriate diagnostic information.
	6. Drivers Assistance System Module (DASM) is inoperative on the bus or a loss of Controller Area Network-Chassis (CAN-C) bus communication.	6. Using the diagnostic scan tool, confirm the DASM is offline and test the CAN-C bus system.
	7. Ineffective ground circuit to the DASM.	7. Test and repair open ground circuit to the DASM as required.
	8. Ineffective feed circuit to the DASM.	8. Test and repair open fused run relay output circuit to the DASM if required.
	9. DASM imager lens dirty or obstructed.	9. Clean imager lens and windshield or remove obstructions from the windshield glass if required.
	11. DASM is in a limited function mode.	11. Use a diagnostic scan tool and check for Diagnostic Trouble Codes (DTC) (s) relative to DASM reliant components.

AUTO HIGH BEAM CONTROL - CRVMM EQUIPPED

CONDITION	POSSIBLE CAUSES	CORRECTION
AUTO HIGH BEAM CONTROL SYSTEM IS INOPERATIVE.	1. Feature is not enabled.	1. Enable Auto Low/High using the customer programmable features function located within the radio.
	2. Automatic headlamps are not turned ON .	2. Turn automatic headlamps ON using the control knob of the headlamp switch.
	3. Headlamp high beams are not selected.	3. Turn high beam headlamps ON using the stalk.
	4. Vehicle speed is below 21 kilometers per hour (km/h) (14 miles per hour/mph).	4. Increase vehicle speed. This system designed to operate at speeds at or above 24 km/h (16 mph).
	5. Incorrect BCM configuration.	5. Use a diagnostic scan tool to check and correct the BCM configuration settings if required. Refer to the appropriate diagnostic information.
	6. CRVMM is inoperative on the LIN bus or a loss of LIN bus communication.	6. Using the diagnostic scan tool, confirm the CRVMM is offline and test the LIN bus system.
	7. Ineffective ground circuit to the CRVMM.	7. Test and repair open ground circuit to the CRVMM as required.
	8. Ineffective feed circuit to the DASM.	8. Test and repair open fused run relay output circuit to the DASM if required.
	9. CRVMM imager lens is dirty or obstructed.	9. Clean imager lens and windshield or remove obstructions from the windshield glass if required.

The BCM receives the AHCM status from the CRVMM on the LIN bus. The BCM also acquires and gates messages to the CRVMM regarding operating conditions and vehicle parameters.