A transient high tension (25,000 V) occurs at the
bulb sockets of the high intensity discharge
(HID) lamps when the combination light switch
is turned ON. It may cause serious electrical
shock or electrocution if you do not observe the
cautions below.

CAUTION

•

Never turn on the combination light switch
before fitting the HID bulbs to their bulb
sockets and completing the reassembly of
the headlight assembly.

•

Do not service the headlight assembly in wet
conditions, such as rain or snow, near a
sprinkler system, or when your hands are
wet to prevent electrocution.

•

Do not touch the surface of the HID bulbs
with your bare hands and do not stain it with
any oils or fats.

•

Do not disassemble the inverter unit and the
igniter unit.

•

Do not turn on the HID bulb by using a power
source other than the battery mounted on the
vehicle.

Low Beams

The headlight low beam and high beam relays
receive battery voltage at all times. When you turn
the headlight switch to the HEAD position with the
dimmer switch in LOW, ground is applied through
the BLU/RED wire and lighting diode to the coils of
the headlight low beam and high beam relays. The
relays are then energized, applying battery voltage
to the left and right low and high beam headlights
through fuses 45, 46 and 48, 49 respectively. The
low beam bulbs come on because they are
individually grounded by G301 and G201. The high
beams and indicator remain off because their
ground path is interrupted by the deenergized
dimmer relay.

High Beams

When you pull the dimmer switch to HIGH with the
low beams already on, ground is applied to the
dimmer relay from the dimmer switch. This
energizes the dimmer relay, applying ground to the
high beam bulbs and high beam indicator, which
turns on the high beams and indicator light. The low

beams go off because their ground path is
interrupted by the activated dimmer relay.

Flash-to-Pass

When you hold the flash-to-pass switch in the ON
position, ground is applied through the BLU/RED
wire and lighting diode to the coils of the headlight
low beam and high beam relays and through the
RED/BLU wire to the coil of the dimmer relay. This
energizes the headlight low beam and high beam
relays, applying battery voltage to the low and high
beam bulbs and to the dimmer relay. As the high
beam bulbs receive battery voltage, the dimmer
relay is energized, applying ground to the high
beam bulbs and high beam indicator, which turns
on the high beams and indicator light. The low
beams go off because their ground path is
interrupted by the activated dimmer relay.

Automatic Lighting

When you move the headlight switch to the AUTO
position, the automatic lighting control unit will
automatically turn on the headlights.

The automatic lighting control unit receives battery
voltage through fuse 56 at all times and receives
battery voltage through fuse 20 with the ignition
switch in ON (ll) and START (lll). When the ignition
switch is turned to ON (ll), the automatic lighting
control unit receives an “ignition on” signal through
fuse 19. When the headlight switch is in the AUTO
position with the driver’s door closed, and if the
automatic lighting sensor detects low ambient light,
the automatic lighting control unit will apply ground
to the BLU/RED wire and lighting diode and ground
the headlight low beam and high beam relays. The
relays energize and cause the high or low beam
headlights to come on, depending on the position of
the dimmer switch. The headlights will operate as if
they had been turned on with the headlight switch.
When the driver’s door is open, ground is applied to
the automatic lighting control unit through the
GRN/BLU wire. When the control unit receives this
ground signal, it removes ground from the headlight
relay and causes the headlights to turn off. The
automatic lighting control unit will also turn off the
headlights if the ambient light levels rise to daylight
conditions or if the headlight switch is moved out of
the AUTO position.

Refer to the Service Manual (Section 23, Electrical) for
specific tests and troubleshooting procedures.

2004 American Honda Motor Co., Inc.

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