Headlamp: Description and Operation

Exterior Lights

How the Circuit Works

The MICU and the combination light switch control the headlights circuit. The low beam and high beam headlight transistors are located within the MICU.

Power Supply

Fuses 18 and 21 (in the under-dash fuse/relay box) supply battery voltage at all times to the low beam and high beam headlight transistors located within the MICU.

When the ignition switch is in the ON position, fuse 37 (in the under-dash fuse/relay box) supplies battery voltage to the DRL control circuit located within the MICU.

System Description

Low Beams

When the headlight switch is moved to the ON position, the combination light switch provides a signal to the MICU to energize the low beam transistors (located inside the MICU). The energized transistors supply voltage to the low beam headlights.

High Beams

When the headlight switch is moved to the ON position, and the dimmer/flash-to-pass switch is moved to the HIGH position, the combination light switch provides a signal to the MICU to energize the high beam and low beam transistors (located inside the MICU). The energized transistors supply voltage to the high and low beam headlights.

Flash-to-Pass

When the dimmer/flash-to-pass switch is moved to the PASSING position, the combination light switch provides a signal to the MICU, energizing the high beam and low beam transistors (located inside the MICU). The energized transistors supply voltage to the high and low beam headlights.

DRL

The MICU controls DRL operation. The following conditions must be met for the headlights to operate in DRL mode:

- The ignition switch is in the ON (II) position
- The headlight switch is in the OFF position
- The parking brake is released

When all three conditions are met, the MICU will supply a reduced voltage to the high beam headlights.