Headlamp Switch: Description and Operation

The multiplexed headlamp switch is located on the instrument panel. The headlamp switch controls the parking lamps, fog lamps and the headlamps. A separate switch in the module controls the interior lamps and instrument cluster illumination. This switch also contains a rheostat for controlling the illumination level of the cluster lamps.

The multiplexed headlamp switch has an off, parking lamp, fog lamp and a headlamp on position. High beams are controlled by the multiplexed multifunction switch on the steering column. The fog lamps are illuminated by pulling back on the headlamp switch knob when in the parking lamp or headlamp ON position.The headlamp switch cannot be repaired. It must be replaced.

The Instrument Cluster monitors the headlamp and multifunction switch operation. When the headlamp switch is rotated to the parking lamp or On position the Instrument Cluster sends a J1850 message to the Front Control Module, which is mated to the power distribution center to become the Integrated Control Module, to illuminate the appropriate bulbs. When the multifunction switch is activated to the optical horn or high beam position the Instrument Cluster illuminates the high beam indicator and sends a J1850 message to the Front Control Module to illuminate the appropriate bulbs.