Headlamp: Description and Operation

HEADLAMPS

The head lamps may be turned on in two different ways. First, when the driver places the headlamp switch in the HEADLAMP position, for normal operation. Second, with the headlamp switch placed in the AUTO position, for Automatic Lamp Control (ALC). During ALC control the headlamps will be in Day Time Running Lamp (DRL) operation in daylight conditions, or low beam operation in low light conditions.

Battery positive voltage to the headlamp switch is supplied by the TBC fuse in the IP fuse block. When the headlamp switch is in the HDLP position, the headlamp power relay coil is energized. A voltage signal is also sent to the Body Control Module (BCM) signaling that the headlamp switch is activated. Battery positive voltage is supplied to the headlamp power relay by the LIGHTING fuse in the underhood fuse block. The headlamp power relay coil is grounded at G101. When the headlamp power relay is energized, the relay supplies battery voltage to the HEADLAMP Fuse LH and HEADLAMP Fuse RH in the underhood fuse block. Both low and high beam headlamps are grounded by the multifunction headlamp dimmer switch in the their respective position through the normally closed DRL relay in the body relay block to G110.

The export vehicle headlamps function the same way as the domestic except the DRL relay is deleted out of the circuit.