Operation CHARM: Car repair manuals for everyone.

Headlamp: Description and Operation

The headlamps may be turned on two different ways. First, when the driver places the headlamp switch in the ON position, for normal operation. Second, with the headlamp switch placed in the OFF position, during automatic headlamp operation in low light conditions.

The HDLP left fuse and the HDLP right fuse in the underhood fuse block, supply battery positive voltage to both low beam lamps and high beam lamps at all times. The low beam and high beam circuits continue to the headlamp switch. When the headlamp switch is placed in the ON position, it provides a ground path for the low beam or high beam lamps through G201. The headlamp switch also provides a input signal to the Body Control Module (BCM) in order to determine if the headlamps are ON.

The automatic headlamps operate in low light conditions, the BCM will pull the headlamp relay control circuit low, energizing the relay. When the headlamp relay energizes, the relay provides a ground path for the low beam or high beam lamps through G201, depending on the headlamp switch position.

Both the headlamp switch and the headlamp relay can provide a ground for the headlamps for manual or automatic headlight operation. The headlights may be switched to high beam by pulling the headlamp switch handle toward the driver until the high beams are activated. When the headlamp switch is placed in the HIGH BEAM position, the indicator lamp and the high beam lamps are grounded and illuminate.