Part 2

Exterior Lighting

HEADLAMP ASSEMBLY

General
Two types of headlamp are available; Bi-xenon or Adaptive Front lighting System (AFS).
The headlamps are located on the bonnet locking platform. Each headlamp is secured at the top to the bonnet locking platform with 1 screw, 1 screw at the bottom to the front bumper support bracket, 1 screw on the fender edge bracket and 1 screw on the headlamp mounting panel. Headlamp removal is facilitated by removal of the radiator grille, front bumper and removal of the 4 headlamp attachment screws.
Headlamp removal is not required for replacement of the xenon or halogen bulbs. The rear of the headlamp unit has removable access covers which allow access to the bulbs and tourist lever.
A large cover, which is rotated counter-clockwise to remove, allows access to the low/high beam xenon bulb.
A second cover, on the inboard side of the headlamp, can be removed to allow access to the high beam 'fill-in' lamp halogen bulb. The bulb is mounted in a holder with an extended end to aid removal.
The turn signal indicators, side lamps, static bending lamp (where fitted) and the side marker lamp (where fitted) are LED's. None of the LED's are serviceable items.
In all markets except NAS, the headlamps have two adjustment screws which allow for the manual setting of the vertical and horizontal beam alignment. A 6mm Allen key is used to rotate the adjusters to achieve the required setting. The inboard adjuster controls the vertical aiming and the outboard adjuster controls the horizontal aiming.
On NAS vehicles the headlamp is regarded as 'Visual Optically Left' (VOL) aiming. There is no horizontal adjustment. Refer to the Service Repair Procedures manual for headlamp alignment data and procedures.
Each headlamp has an integral sixteen pin connector which provides inputs and outputs for the various functions of the headlamp assembly. The usage of the pins differs between model variants. Refer to the Electrical Library and circuit diagrams for pin details.
Two breathers are located on the rear of the headlamp housing. The Goretex breathers allow air flow in and out of the headlamp but prevent the ingress of moisture from rain, road spray or washing. If condensation occurs within the headlamp, check that the breathers are not blocked with mud etc before further action is taken.

Headlamp Operation
The lamps contained within the headlamp assembly have differing functionality depending on the function selected.
The low beam headlamps are switched on when the ignition is in power mode 6 (ignition on) and:
- the lighting control switch is the headlamp position or
- the lighting control switch is in the 'AUTO' position and a 'lights on' signal is received by the CJB from the rain/light sensor.
The low beam headlamps can also be operated by the headlamp delay feature.
The high beam headlamps are switched on when the ignition is in power mode 6 (ignition on) and:
- the lighting control switch is in the headlamp position or the headlamps are activated by the AUTO feature and the left hand steering column multifunction switch is pushed forward, away from the driver or
- the headlamp flash function is operated by pulling the left hand steering column multifunction switch towards the driver or
- the auto high beam system is active.

Common Headlamp Features
Turn Signal Indicators
The turn signal indicator LED's are located in 3 rows of 4 LED's in the outer part of the headlamp assembly. The LED's are not serviceable components. The LED's are controlled by an LED control module located at the rear of the headlamp assembly.
Side Lamps
The side lamp LED's are located in a circular pattern around the circumference of the both the xenon projector module (8 LED's) and the halogen high beam fill-in lamp (6 LED's). The LED's are not serviceable components. The LED's are controlled an LED control module located at the rear of the headlamp assembly.
Side Marker Lamps (NAS only)
The side marker lamp LED is located in a molded receptacle in the outer edge of the headlamp. The side marker lamp illuminates a small rectangular section between the orange side reflectors on the outside of the headlamp. The LED is not a serviceable component.
Tourist Lever
A tourist lever mechanism is located on the side of the xenon projector module. This mechanism moves a flap to blank off a portion of the beam spread to enable the vehicle to be driven in opposite drive hand markets without applying blanking decals to the headlamp lens.
The position of the tourist lever varies between headlamp variants and drive hand markets. The following lists detail the lever location and positions for home and opposite drive hand markets.
For RH side headlamps, the tourist function is operated by pushing up the lever. The delivery condition is with the tourist lever pushed down. For LH (left-hand) side headlamps , the tourist function is operated by pushing the lever down. The delivery condition is with the tourist lever pushed up.

Bi-Xenon / AFS Headlamps
- UK Left Hand (LH) side headlamp: tourist lever on the fender side
- UK Right Hand (RH) side headlamp: tourist lever on the grille side
- ROW LH side headlamp: tourist lever on the grille side
- ROW RH side headlamp: tourist lever on the fender side
For all xenon and AFS headlamp variants the tourist function is operated by pushing the lever down. The delivery condition is with the tourist lever pushed up.

Static Headlamp Leveling - Xenon Headlamps
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.

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 D3S 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 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 55W 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' (the Bi-Xenon trademark is the property of Hella KGaA Hueck & Co., Germany) 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 CJB 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 D3S xenon bulb incorporates an integral igniter unit and both components must be replaced if the bulb fails.

Xenon/Halogen Headlamp Beam Comparison









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. 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 2.6A which gives a lamp output of 75W. During this phase, the xenon gas begins to illuminate brightly and the environment within the bulb stabilizes 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 35W. The process from start-up to continuous phase is completed in a very short time.
The xenon system is controlled by the CJB, the two xenon control modules and the two igniters. The xenon control modules (one per headlamp) receive an operating voltage from the CJB 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.

Adaptive Front Lighting System (AFS) Headlamps
The AFS headlamp is similar in its construction to the xenon headlamp described previously. The projector module is constructed and operates as described for the xenon headlamp with the addition of the AFS system which allows the projector module to be moved vertically and horizontally by stepper motors. The following description covers the additional differences to the xenon headlamp with AFS.
The AFS is a system to improve driver visibility under differing driving conditions. AFS provides a larger visible area which is illuminated when cornering by adjusting the position of the beam distribution on the road. Horizontal adjustment is made automatically to the most suitable orientation for the driving conditions using steering angle and information from other vehicle sensors.
AFS includes the dynamic headlamp leveling system described in the 'Headlamp Leveling' section of this document. The bi-xenon module within the headlamp is controlled by actuator motors which rotate the projector module on its vertical and horizontal axes to adjust the beam output to suit the cornering conditions and vehicle inclination. Only the bi-xenon lamp projector module swivels, the halogen high beam lamp unit remains static.
The AFS is controlled by an AFS control module which is located on the instrument panel frame, behind the glove compartment. The module is connected to and controls an AFS power module located inside the headlamp housing. Signals from the AFS control module are processed by the AFS power module which powers stepper motors to adjust the vertical and horizontal alignment of the projector module. The AFS power module also controls and regulates the operation of the static bending lamp (if fitted) which is requested by the AFS control module but controlled by the CJB.

AFS Concept









The AFS xenon headlamp construction is similar to the non-AFS xenon headlamp assembly. The AFS headlamp has a xenon control module located on the underside of the lamp assembly. An additional AFS power module is located inside the headlamp housing. The AFS power modules supply the correct voltage to the stepper motors which control the positioning and movement of the AFS projector module.
The AFS assembly contains an additional carrier frame which provides the location for the AFS actuators. The remaining lamps are as described previously for the xenon headlamp. The AFS headlamp also incorporates a static bending/cornering lamp (except on NAS market vehicles).
The carrier frame is attached to the AFS vertical actuator. The projector module has a central pivot point which allows the module to move horizontally in response to operation of the AFS horizontal actuator.
The AFS actuators are bi-polar (2 phase) dc stepper motors which are driven by a power output from the AFS power module. Each stepper motor receives its position information from the AFS control module via the applicable AFS power module. When the actuators are powered to their requested positions, a holding current is applied to maintain the actuator position.
The actuators do not supply a positional feedback signal to the AFS control module. Each stepper motor requires referencing each time the AFS system becomes active. When the AFS system is active, each vertical actuator is driven in the low beam position and each horizontal actuator is driven to an inboard position until a mechanical stop in the actuator is reached. Once the stop is reached a step counter in the AFS control module is set to zero and the actuator is then powered to the operating position as determined by the AFS control module software.
The AFS control module receives front and rear suspension height data and vehicle speed signals from the ABS module to adjust the projector module vertically to increase the beam range as the vehicle speed increases.

AFS Control Module
The AFS control module is located on the instrument panel frame, behind the glove compartment.
The AFS control module is a dual functionality unit which also incorporates software to control the dynamic headlamp leveling. The AFS control module is connected to the high speed CAN bus and receives inputs from other vehicle systems on the status of the following parameters:
- Steering angle
- Vehicle speed
- Headlamp status
- Engine running
- Reverse gear selected
- Automatic lighting on.
The AFS will only operate when the AFS control module receives an engine running signal on the CAN bus. When the engine running signal is received the AFS control module performs an initialization routine.
The AFS will also function when the lighting control switch is in the AUTO position and the AFS control module receives a lights on signal from the rain/light sensor and an engine running signal.
The AFS control module then monitors the inputs from the other vehicle systems to control the AFS functionality according to cornering (steering) angles and vehicle speed.
The AFS control module is connected to each AFS power module on a private Local Interconnect Network (LIN) bus. The power modules read operating values supplied from the AFS control module and control the output drivers for the stepper motor actuators inside the headlamp assembly.