Headlights (USA)

Exterior Lights

How the Headlights Circuit Works (USA)

The headlight circuit is controlled by the MICU system. The high beam and low beam headlight relays are located within the relay control module. Refer to the multiplex Diagram Set for more multiplex information.

Power Supply

With the ignition switch in the ON (II) or START (III) position, battery voltage is applied through fuse 21 (in the under-dash fuse/relay box) to the MICU and to the combination switch control unit.

Fuse 7 (in the under-dash fuse/relay box) is hot at all times and supplies battery voltage to the to the MICU and to the combination switch control unit.

System Description

High and Low Beams

The high and low beam headlight relays are located within the relay control module (in under-hood fuse/relay box). The relays receive battery voltage at all times. The grounding and operation of the relays are controlled by the multiplex system.

The combination switch control unit in the steering column receives information signals about operating conditions from the headlight switch and from the dimmer switch.

When headlight switch is turned on, and the dimmer switch is set to the high or low beam position, the information from both switches is processed by the combination switch control unit and transmitted from control unit-to-control unit across the multiplex communication lines. The relay control module will then ground the appropriate high or low beam relay to operate the necessary headlights.

Because of the multiplex operation of the headlights, the headlights will always reset to low beams when the ignition key is cycled.

Flash-to-Pass

The combination switch control unit in the steering column receives information signals about operating conditions from the headlight switch and from the dimmer switch.

When the dimmer switch is pulled back and moved to the flash-to-pass position, the information from the dimmer switch is processed by the combination switch control unit and transmitted from control unit-to-control unit across the multiplex communication lines. The relay control module will then ground the high beam relay to operate the passing lights.