Headlamp: Description and Operation

HEADLAMPS

The headlamps may be turned ON 2 different ways. First, when the driver places the headlamp switch is placed in the ON position, for normal operation. Second, with the headlamp switch placed in the OFF 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.

The HEADLAMP circuit breaker supplies batter positive voltage to the headlamp switch at all times. When the headlamp switch is in the OFF or PARK position, the headlamp switch supplies a battery positive headlamps OFF signal circuit to the DRL control module. When the headlamp switch is placed in the HEAD position, battery positive voltage is applied to the headlamp switch signal circuit. The headlamp switch signal circuit is applied to the headlamp dimmer switch. Depending on the headlamp dimmer switch position, battery positive voltage is then applied to the either the high beam headlamp circuit or the low beam headlamp circuit. For the high beam circuit battery positive voltage is then applied to the instrument cluster for the high beam indicator, to the HUD for the high beam indicator and through the underhood fuse block to both left and right high beam headlamps. For the low beam headlamps battery positive voltage is applied from the headlamp dimmer switch to the underhood fuse block to both the left and right low beam headlamps. The ground for the headlamps is applied from G101.

If the headlight switch is left in the ON position, the inadvertent power control feature will turn off the headlights 10 minutes after the ignition switch is turned to the OFF position. If the driver places the headlight switch in the ON position after the ignition switch has been turned OFF, or if the ignition switch is in the ACCY position, the headlights will remain on until turned off or the battery runs dead.