Exterior Lighting - System Operation and Component Description

changes the headlamp beam pattern when activated. The solenoid and shutter are not serviceable separately from the headlamp assembly. The headlamp assembly is provided power on independent circuits for the low beams and the high beams.

The High Intensity Discharge (HID) headlamp also contains LED signature lamps (except China).

For China vehicles, the headlamp assemblies contain vertical headlamp adjustment actuators for the manual headlamps leveling system.

A ballast is mounted to each headlamp assembly to power the High Intensity Discharge (HID) bulb.

Exterior lamps are vented to accommodate normal changes in pressure. Condensation can be a natural by-product of this design. When moist air enters the lamp assembly through the vents, there is a possibility that condensation can occur if the temperature is cold. When normal condensation occurs, a thin mist forms on the interior of the lens. The thin mist eventually clears and exits through the vents during normal operation. The amount of time it takes to clear the lens of acceptable mist varies with ambient humidity and lamp types. Normal condensation clears from any lamp in 48 hours under dry conditions.

Do not replace a lamp assembly with acceptable levels of condensation such as:

presence of thin mist (no streaks, drip marks or droplets are present) fine mist covers less than 50% of the lens

Examples of unacceptable moisture (usually caused by a lamp housing leak):

water puddling inside the lamp large water droplets, drip marks or streaks present on the interior of the lens

Headlamp Switch

The BCM monitors the headlamp switch position by sending voltage signals on multiple circuits to the headlamp switch. There is one circuit for each headlamp switch position. At any given time, one of the signal circuits is switched to ground to indicate the headlamp switch position.

Ballast

A ballast is mounted to each High Intensity Discharge (HID) headlamp assembly. The ballasts provide high voltage to the High Intensity Discharge (HID) bulbs when voltage from the BCM (low beam outputs) is detected.

Light Sensor

The BCM sends a voltage signal to the light sensor. The light sensor provides resistance between the voltage signal and ground. The resistance varies depending on the amount of ambient light detected by the light sensor. The brighter the ambient light, the lower the resistance. By varying the resistance, the BCM can determine the amount of ambient light.

Stoplamp Switch

The stoplamp switch is a normally open switch and is provided voltage at all times. When the brake pedal is applied, the switch closes and routes voltage to the BCM.

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