Headlamp: Description and Operation

HEADLAMPS

The headlamps may be turned ON in 3 different ways:
- When the headlamp switch is placed in the ON position, for normal operation.
- With the twilight switch placed in the ON position, for automatic lamp control (ALC).
- With the twilight switch placed in the ON position, with the windshield wipers ON in daylight conditions, after a 6 second delay. 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 lamp control module (LCM) provides battery positive voltage to the signal circuits of the headlamp switch and headlamp dimmer switch. The circuits include the headlamp switch headlamps on signal, the headlamp switch flash-to-pass signal and the headlamp dimmer switch high beam signal. When the headlamp switch is ON, a ground path is available for the headlamp switch headlamps on signal circuit of the LCM through the headlamp switch. The LCM provides battery voltage to the headlamp low beam supply voltage circuit or the headlamp high beam supply voltage circuit, if the headlamps are necessary.
The position of the headlamp dimmer switch determines which circuit has battery voltage. When the headlamp low beam supply voltage circuit is energized, current flow goes to both low beam fuses. Current flows to the low beam headlamps. The headlamps have ground at G105 and at G106. When the headlamp high beam supply voltage circuit is energized, current flow goes to both high beam fuses. Current flows to the high beam headlamps. The current flow of the left high beam is from the fuse to the left high beam lamp. From the lamp, the current flows to G106 with T62 or the LCM without T62. The current flow of the right high beam is from the fuse to the right high beam lamp. From the lamp, the current flow is to ground at G105.