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 HEADLAMP position, for normal operation. Second, with the headlamp switch placed in the OFF position, for Daytime Running Lamps (DRL) operation in night mode.

The PARK LP fuse and the HEADLAMPS circuit breaker, supply battery positive voltage to the headlamp switch and headlamp dimmer switch. When the headlamp switch is placed in the HEAD position, it provides voltage to the headlamp dimmer switch. The headlamp circuit continues through the headlamp dimmer switch and, depending on the position of the headlamp dimmer switch, is connected to either the low beam or high beam headlamps. The headlamps are grounded at G101 for the LH headlamp and G102 for the RH headlamp.

With the headlamp dimmer switch in the low beam position, the high beams may be momentarily turned on or flashed with the headlamp dimmer switch handle. When the headlamp dimmer switch handle is pulled toward the driver, the flash-to-pass switch closes providing voltage to the high beam circuit. Both high beams will remain on until the driver releases the switch handle. If the low beam headlamps were on during a flash-to-pass operation, they will remain on. The headlights may be switched to high beam by pulling the headlamp dimmer switch handle toward the driver until the headlamp dimmer switch is activated. When the headlamp dimmer switch is placed in the HIGH BEAM position, the high beam circuit provides voltage to the high beam indicator in the IP.

If the headlight switch is left in the ON position, the headlights will remain on until turned off or the battery runs dead.

TAIL, LICENSE LAMPS, AND HEADLAMP POSITION LAMPS (EXPORT)

The tail lamps, headlamp position lamps, and license lamps, are turned on when the headlamp switch is placed in either the PARK or HEAD position, or anytime the headlights are requested. With the headlamp switch placed in the OFF position, and the engine running, the Daytime Running Lamps (DRL) control module will operate the tail lamps. The PARK fuse supplies battery voltage to the headlamp switch and DRL module. Current flow is from the headlamp switch to the headlamp position lamps and license lamps. The tail lamps receive the headlamp switch voltage via an inactive DRL control module. For DRL operation current flow is from the DRL control module to the tail lamps only. The LF headlamp position lamp is grounded at G101 and the RF headlamp position lamp is grounded at G102. The remaining lamps are grounded a G401.