Daytime Running Lamp: Description and Operation

WARNING: 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.

High and Low Beams
The headlight relays receive battery voltage at all times. When you turn the headlight switch to the HEAD position, ground is applied through the BLU/RED wire to the coils of the headlight and high beam cut relays. The headlight relays are then energized, applying battery voltage to the left and right low beam headlights, the DRL control unit, and the high beam cut relay through fuses 43 and 45. The DRL control unit provides power to the left and right high beam headlights. The high beam cut relay is energized and the low beam bulbs come on with the dimmer switch in LOW or HIGH because the opposite terminal is tied to ground. The ground path for the high beams and indicator is through the closed contacts of the high beam cut relay and the dimmer switch. With the dimmer switch in LOW the path is interrupted and the high beams remain off, but in HIGH a ground path is provided and the high beams come on.

Flash-to-Pass
When you hold the flash-to-pass switch in the ON position, ground is applied through the BLU/RED wire to the coils of the headlight and high beam cut relays. The headlight relays are then energized, applying battery voltage to the left and right low beam headlights, the DRL control unit, and the high beam cut relay through fuses 43 and 45. The DRL control unit provides power to the left and right high beam headlights. The high beam cut relay is energized and the low beam bulbs come on because the opposite terminal is tied to ground. The high beams and indicator also come on because the opposite terminal is provided a path to ground through the closed flash-to-pass switch and the closed contacts of the high beam cut relay.

Daytime Running Lights
When you turn the ignition switch to ON (II) with the parking brake released, the DRL control unit supplies about 6 volts to the RED/BLU wire (cavity 10), about 12 volts to the RED/WHT wire (cavity 1), and ground to the RED/ORN wire (cavity 11). This provides about 6 volts to both high beam headlights, causing them to come on at reduced brightness. If you apply the parking brake, ground is applied to the DRL control unit at the GRN/WHT wire. If the parking brake is applied before you turn the ignition switch to ON (II), the daytime mode will remain off until you release the parking brake. Once the high beams are in the daytime mode, applying the parking brake will not turn them off. When you switch to low beams, high beams, or flash-to-pass operation, ground is applied to the DRL control unit through the BLU/RED wire, and the control unit then turns off the daytime running lights mode.