Static Headlamp Leveling - Halogen and Xenon Headlamps (Not AFS)
Static Headlamp Leveling - Halogen and Xenon Headlamps (not AFS)
Static vehicle headlamp leveling is performed by the air suspension system and the air suspension control module. The suspension system constantly monitors the vehicle attitude and adjusts the height of the front and/or rear of the vehicle accordingly. This maintains the correct vehicle attitude and consequently maintains the correct headlamp beam alignment.
The vehicle leveling system is fully automatic, therefore the lighting control switch does not have a manual leveling rotary control.
Halogen Headlamps
The mono-halogen low beam only headlamp uses an H7 Long Life (LL) 55 W halogen bulb. The lamp uses a projector lens, similar to the xenon headlamp. The projector module comprises an ellipsoidal lens and a reflector. The projector reflector collects the light produced by the halogen bulb and projects the light into a focal plane containing a shield. The contour of the shield is projected onto the road by the lens. The bulb is retained with conventional wire retaining clips.
A complex surface reflector is used for the halogen high beam 'fill-in' lamp. This type of reflector is divided into separate parabolic segments, with each segment having a different focal length. The high beam 'fill-in' lamp uses a H7LL 55 W halogen bulb. The bulb is retained in an extended holder which allows easy access to the bulb. Once removed, the bulb can be removed from the holder by pulling it from its locating pegs.
Xenon Headlamps
Safety Precautions
WARNING: The Xenon system generates up to 28000 volts and contact with this voltage could lead to fatality. Make sure that the headlamps are switched off before working on the system.
The following safety precautions must be followed when working on the xenon headlamp system:
^ DO NOT attempt any procedures on the xenon headlamps when the lights are switched on
^ Handling of the D1S xenon bulb must be performed using suitable protective equipment, e.g. gloves and goggles. The glass part of the bulb must not be touched
^ Xenon bulbs must be disposed of as hazardous waste
^ Only operate the lamp in a mounted condition in the reflector.
The xenon headlamps use a complex surface reflector for the halogen high beam 'fill-in' lamp. This type of lamp has the reflector divided into separate parabolic segments, with each segment having a different focal length. A halogen H7LL 55 W bulb is retained in an extended holder. The holder is secured in the rear of the high beam 'fill-in' lamp lens by rotating clockwise.
The xenon headlamp is known as 'bi-xenon' because it operates as both a low and high beam unit. The xenon bulb is located in a projector module which comprises an ellipsoidal lens with a solenoid controlled shutter to change the beam output from low to high.
NOTE: If the lighting control switch is in the 0 (off) position, the xenon lamps do not operate when the high beam 'flash' function is operated. If the lighting switch is in the headlamp position or the 'AUTO' position with the low beam headlamp active, the xenon low beam will remain on when the high beam 'flash' function is operated.
The xenon headlamp system is controlled by the LCM using a xenon control module and an igniter for each headlamp. The xenon control modules and the igniters provide the regulated power supply required to illuminate the xenon bulbs through their start-up phases of operation.
The xenon bulb is located in the rear of the projector module. The D1S xenon bulb incorporates an integral igniter unit and both components must be replaced if the bulb fails. A plastic mounting ring is fitted to the bulb and secures the bulb in the rear of the projector module. The mounting ring must be removed from the bulb and fitted to the replacement bulb.
The mounting ring locates in mating cut-outs in the xenon bulb. Refer to the illustration that follows for correct removal and replacement of the mounting ring.
Xenon Bulb Mounting Ring Replacement
Xenon/Halogen Headlamp Beam Comparison
The xenon low/high beam headlamps use ellipsoidal technology for the lens and reflector providing improved night time visibility compared to conventional halogen headlamps. The xenon headlamps provide the following benefits when compared to halogen headlamps:
^ Longer bulb life - Approximately 3 to 5 times longer than a halogen bulb
^ Increased light output - xenon headlamps output 3 to 4 times more light on the road surface than halogen headlamps Blue/White light which is closer to natural daylight - compared to a yellow light produced by a halogen bulb
^ Improved night time driving visibility - xenon lamps produce a wider and brighter beam in front of the vehicle than conventional halogen bulbs
^ Lower running temperatures
^ Lower power consumption.
The xenon headlamp is a self contained unit located within the headlamp assembly. The unit comprises a reflector, an adaptor ring, the lens, a shutter controller and the xenon bulb, which as an assembly is known as the projector module.
The reflector is curved and provides the mounting for the xenon bulb. The bulb locates in a keyway to ensure correct alignment in the reflector and is secured by a plastic mounting ring. The bulb is an integral part of the igniter and is electrically connected by a connector located in the igniter unit.
The shutter controller is a solenoid which operates the shutter mechanism via a lever. The shutter is used to change the beam projection from low beam to high beam and visa versa.
The xenon bulbs illuminate when an arc of electrical current is established between two electrodes within the bulb. The xenon gas sealed in the bulb reacts to the electrical excitation and the heat generated by the current flow to produce the characteristic blue/white light.
To operate at full efficiency, the xenon bulb goes through three stages of operation before full output for continuous operation is achieved. The three phases are; start-up phase, warm-up phase and continuous phase.
In the start-up phase, the bulb requires an initial high voltage starting pulse of up to 30000 volts to establish the arc. This is produced by the igniter. The warm-up phase begins once the arc is established. The xenon control module regulates the supply to the bulb to 2.6 A which gives a lamp output of 75 W. During this phase, the xenon gas begins to illuminate brightly and the environment within the bulb stabilises ensuring a continual current flow between the electrodes. When the warm-up phase is complete, the xenon control module changes to continuous phase. The supply voltage to the bulb is reduced and the operating power required for continual operation is reduced to 35 W. The process from start-up to continuous phase is completed in a very short time.
The xenon system is controlled by the LCM, the two xenon control modules and the two igniters. The xenon control modules (one per headlamp) receive an operating voltage from the LCM when the headlamps are switched on. The modules regulate the power supply required through the phases of start-up.
The igniters (one per headlamp) generate the initial high voltage required to establish the arc. The igniters have integral coils which generate high voltage pulses required for start-up. Once the xenon bulbs are operating, the igniters provide a closed circuit for regulated power supply from the control modules.