Honda Accord: System Description - Exterior Lights - Body Electrical - Honda Accord MK8 2008-2012 Service ManualHonda Accord: System Description

Headlights System Description

The headlight system Is composed of the driver's MICU, the passenger's MICU, the headlight and dimmer/flash-to-pass switches (Inside the combination light switch), the left and right headlights, and the high beam Indicator.

Each MICU controls each side of the headlights with a built-in low beam control circuit and a built-in high beam control circuit based upon the position of the headlight and dimmer/flash-to-pass combination light switches. The taillights and license plate lights are controlled by the driver's MICU only.

Low Beams.

When you move the headlight switch to the ON position and the dimmer/flash-to-pass switch to the low position, a ground signal Is supplied to terminal No. 8 of driver's under-dash fuse/relay box connector R (24P). The driver's MICU then energizes the low beam control circuit, supplying battery voltage to the low beam of the left headlight, turning it on.

Also the driver's MICU sends the message to the passenger's MICU via the B-CAN communication lines. The passenger's MICU then energizes the low beam-control circuit, supplying battery voltage to the low beam of the right headlight, turning it on.

High Beams

When you move the headlight switch to the ON position and the dimmer/flash-torpass switch to the high position, ground signals are supplied to terminals No. 8 and No. 22 of driver's under-dash fuse/relay box (driver's MICU) connector R (24P). The driver's and passenger's MICUs then energize the each side of the high beam headlight control circuits, supplying battery voltage to the high beam headlights, turning them on.

Flash-to-Pass

When you pull the dimmer/flash-to-pass switch to the passing position, a ground signal is supplied to terminal No. 21 of the driver's under-dash fuse/relay box (MICU) connector R (24P). The driver's and passenger's MICUs then energize the high beam control circuits for as long as the switch is held, supplying battery voltage to the high beam headlights, turning them on.

Daytime Running Lights System Description

The daytime running lights system includes the driver and passenger's MICUs, the left and right high beam headlights, the parking brake switch, and the DRL indicator. The daytime running lights operate with the ignition switch ON (II), the headlights off (headlight switch OFF or in the parking position), and the parking brake released.

When the daytime running lights are on, the MICU turns the high beam headlight control circuit on and off (duty cycle), which provides a reduced voltage (approximately 6—8 volts) to the high beam headlights (via the No. 1 and No. 28 fuses in the driver's under-dash fuse/relay box and No. 1 fuse in the passenger's under-dash fuse/relay box); the high beam headlights come on with reduced brightness. The gauge control module controls the DRL indicator to turn it on.

NOTE: • The daytime running lights are disabled when the ignition switch is turned to LOCK (0). To keep the daytime running lights from coming on, apply the parking brake switch while the ignition switch is in LOCK (0) position. When you then turn the ignition switch back to ON (II), the daytime running lights will not come on until the parking brake is released.

• The headlights revert to normal operation when you turn them on with the headlight switch.

    Component Location Index
    4-door   4-door 2-door 2-door ...

    Circuit Diagram
    With automatic lighting Without automatic lighting Back-up Lights Brake Lights ...

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