Land Rover Discovery Owners & Service Manuals

Land Rover Discovery: Halogen / Xenon Headlamp

Halogen Headlamp

Halogen headlamp

  1. Projector module - low/high beam headlamp
  2. Daytime Running Lamp (DRL) LED
  3. Turn signal indicator
  4. Side marker lamp LED (NAS only)
  5. Amber side reflector (NAS only)
  6. Headlamp mounting bracket
  7. Halogen bulb access cover
  8. Release lever
  9. Electrical connector
  10. Side marker lamp bulb holder

The halogen headlamp uses a projector module which comprises an ellipsoidal lens with a solenoid controlled shutter to change the beam output from low to high beam.

The halogen 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 halogen bulb, which together forms an assembly known as the projector module. The reflector is curved and provides the mounting point for the xenon bulb.

The HB3 bulb is located in an integral holder which locates in a keyway to ensure the correct alignment in the reflector and is secured by rotating to the locked position. 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 vice versa.

Xenon Headlamp

WARNINGS:

  • 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 a xenon headlamp system:
  • DO NOT attempt any procedures on the xenon headlamps when the lights are switched on.
  • Handling of the xenon bulb must be performed using suitable protective equipment, for example 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.

Xenon Headlamp

  1. Projector module - low/high beam headlamp
  2. Static bending lamp (Not NAS)
  3. Turn signal indicator
  4. Side marker lamp LED (NAS only)
  5. Amber side reflector (NAS only)
  6. Headlamp mounting bracket
  7. Xenon Bulb Control Module (XBCM)
  8. Xenon bulb access cover
  9. Side lamp / Daytime Running Lamp (DRL) LED
  10. Release lever
  11. Electrical connector
  12. Turn signal indicator bulb holder

The xenon headlamp operates as both a low and high beam unit. The unit comprises a reflector, an adaptor ring, the lens, a shutter controller and the xenon bulb, which together is an assembly known as the projector module.

The projector module is installed in a carrier frame that allows the module to tilt for vertical movement of the headlamp beam. Vertical movement is controlled by an actuator, connected between the carrier frame and the projector module, operated by the headlamp Levelling control module for automatic headlamp Levelling.

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 xenon bulb igniter. The shutter controller is a solenoid which operates the shutter mechanism via a lever. The shutter is used to change the beam projection between low and high beam.

The xenon headlamps are controlled by the CJB using a xenon bulb control module and a xenon bulb igniter for each headlamp. These provide the regulated power supply required to illuminate the xenon bulbs through their start-up phases of operation.

The xenon bulbs illuminate when an arc of electrical current is established between 2 electrodes within the bulb. The xenon gas sealed in the bulb reacts to the electrical excitation and the heat generated by the current flow produces the characteristic blue/white light.

To operate at full efficiency, the xenon bulb goes through 3 stages of operation before the output for continuous operation is achieved. The 3 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 28000 volts in order to establish the arc. This high voltage starting pulse is produced by the igniter and, once the arc is established, the warmup phase begins. During the warm-up phase, the xenon bulb control module regulates the supply to the bulb to 2.6A which gives a lamp output of 75W. While in this phase, the xenon gas begins to illuminate brightly and the environment within the bulb stabilizes, ensuring a continual current flow between the electrodes. Once the warm-up phase is complete, the xenon bulb 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 bulb 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 xenon bulb igniters (one per headlamp) generate the initial high voltage required to establish the arc. The igniters have integral coils which generate the high voltage pulses required for start-up. Once the xenon bulbs are operating, the igniters provide a closed circuit for the regulated power supply from the xenon bulb control modules.

Static Bending Lamps (Xenon Only)

The LED static bending lamps are designed to illuminate the direction of travel when cornering at low speeds. The static bending lamp functionality, which is controlled by the CJB and the HLCM, operates using inputs from the steering angle sensor and vehicle speed information from the ABS control module. The static bending lamp is incorporated into the headlamp assembly. The design of the lens projects a spread of light from the vehicle at approximately 45 degrees to the vehicle axis. The static bending lamp uses LEDs located in the headlamp housing.

NOTE:

The static bending lamps are not fitted to NAS vehicles.

The static bending lamps operate with a steering angle sensor CAN bus signal which is received by the CJB. The CJB monitors this signal and vehicle speed and activates the static bending lamp LED. When the operation parameters of the lamp are reached, the CJB snaps the static bending lamp LED on. When the lamp is switched off, the CJB fades the LED off by decreasing the Pulse Width Modulation (PWM) voltage in a linear manner over a period of 1 second. The static bending lamps can only be active for a maximum of 3 minutes at any given time.

NOTE:

NOTE: Static bending lamps only operate when the transmission is in DRIVE or in SPORT - and the low beam is active.

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