Ambient Light Sensor: Testing and Inspection
Auto Headlamp Sensor (AHL) TestThe auto headlamp sensor is the key sensor for the auto headlamp system. The sensor needs real sunlight to properly register the light level. When auto headlamps are enabled indoors, the headlamps may be turned on. The sensor is located in the center of the defroster grille at the base of the windshield. There are no faults set in the Body Control Module (BCM) for a bad or missing AHL Sensor. Symptom of a missing sensor or unconnected sensor would be that the Headlamps and Parklamps turn ON when the vehicle is started and there is a high level of ambient light present (ie. daytime). Auto headlamps should not function in the presence of daylight.