Land Rover Discovery Owners & Service Manuals

Land Rover Discovery: Headlamp Assemblies/ Description

HEADLAMP ASSEMBLIES

Three headlamp variants are available depending on model specification:

  • halogen,
  • xenon,
  • xenon with Adaptive Front lighting System (AFS).

The headlamps are sealed units, with scratch resistant polycarbonate lenses bonded to the headlamp body. One sealed access cover and a sealed bulb holder provide a watertight environment for the headlamp internal components. To prevent fogging of the lens and to allow the headlamp unit to 'breath' in response to internal temperature changes, a vent is located at the outer rear face of the headlamp body. The vent is covered by a Gortex waterproof membrane. This allows ventilation of the headlamp while preventing the ingress of water.

Each headlamp has one access cover at the rear and a turn signal indicator bulb holder. Access to the cover and/or bulb holder requires removal of the grille and headlamp screws. A release lever at the rear of the headlamp allows the headlamp assembly to be released from its guide slots in the headlamp mounting bracket and moved forwards to allow access to the cover and the turn signal indicator bulb. The cover is removed by rotating clockwise to allow access to the xenon or halogen bulb.

On NAS vehicles, the side marker lamp LED is coloured orange. The side marker lamp lens is designed so that light from the LED also illuminates the orange coloured side marker reflector area at the side of the lamp without the need for an additional bulb.

Headlamp Levelling

Headlamp Levelling provides for the adjustment of the vertical aim of the headlamps to minimize glare to other road users when the vehicle attitude changes due to vehicle loading.

Two types of headlamp Levelling are available dependent on the type of headlamps fitted to the vehicle:

  • Manual headlamp Levelling - Halogen headlamps only
  • Automatic headlamp Levelling - Xenon headlamps only.

Manual Headlamp Levelling - Halogen Headlamps Only

The manual system comprises the following components:

NOTE:

NOTE: Headlamp leveling is not available on NAS vehicles with halogen headlamps.

  • Two headlamp Levelling motors
  • Headlamp Levelling rheostat rotary control.

A rotary thumbwheel controller is located adjacent to the instrument panel dimmer control in the auxiliary lighting switch. The rotary thumbwheel controller is connected to a rheostat which gives a variable output to the headlamp Levelling stepper motors. The motors respond to the output and move to adjust the headlamp vertical alignment as required.

In power mode 6 or above the motors in the lamps are driven from the extended ignition relay in the CJB, via a fuse to each lamp motor.

Movement of the Levelling rotary control produces a variable voltage output (hardwire connection). The motors react to the supplied voltage and move the headlamp to the requested position which relates to the supplied voltage from the Levelling rotary control. The headlamps can be lowered from their unladen position to compensate for changes in vehicle attitude due to loading.

The control has four defined positions to compensate for a drop in height at the rear of the vehicle and avoid dazzle to oncoming drivers. The positions are defined as follows:

Manual Headlamp Levelling - Halogen Headlamps Only

Manual Headlamp Levelling - Halogen Headlamps Only

Headlamp Delay

The CJB controls a headlamp delay function which illuminates after the occupants leave the vehicle. The headlamp delay will operate on low beam headlamps only when the lighting control switch is in the AUTO position and the ignition is off (power mode 0) or in accessory power mode 4.

The headlamp delay is activated when the lighting control switch is in the AUTO position and the engine is switched off. The message centre displays a 'HEADLIGHT DELAY' message and the low beam headlamps will be activated for a period of approximately 30, 60 or 120 seconds. After the delay period, the CJB automatically switches off the delay function, extinguishing the headlamps. The delay period can be adjusted using the instrument cluster 'Vehicle Settings' menu. The feature can also be disabled using this menu.

The headlamp delay feature can also be switched on when approaching the vehicle or switched off by pressing the headlamp switch on the smart key.

Automatic Headlamp Levelling - Xenon Headlamps Only

Automatic headlamp Levelling is only available on vehicles with xenon headlamps. The system is not a Dynamic headlamp Levelling system and changes in vehicle inclination due to positive and negative acceleration are not compensated.

Automatic headlamp Levelling provides for the static, periodic adjustment of the vertical aim of the headlamps to minimize glare to other road users when the vehicle attitude changes due to loading.

Automatic headlamp Levelling is controlled by the Headlamp Levelling Control Module (HLCM). The HLCM is a dual function control module which can process and control the headlamp Levelling and the Adaptive Front lighting System (AFS) if fitted.

The headlamp Levelling system comprises the following components and information from other vehicle systems:

  • Front and rear vehicle height sensors
  • Two headlamp Levelling, vertical adjustment motors
  • HLCM
  • Ignition in power mode 6 or above.

When the ignition is in power mode 6 or above, power is supplied, via the extended ignition relay in the CJB, to the lighting control switch, the headlamp Levelling motors (or AFS motors if fitted) and to the HLCM.

When the lighting control switch is moved to the side lamp or headlamp position, a LIN bus message is passed from the clockspring to the CJB for the selected function. The CJB then issues a 'lights on' message on the High Speed CAN Powertrain bus CAN bus to the HLCM.

The HLCM uses signals from the front and rear height sensors to periodically re-align the vertical aim of the headlamps to their optimum position.

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