L322 Range Rover System Description and Operation
LIGHTING
86-2-28 DESCRIPTION AND OPERATION
Low Beam Headlamps
The low beam headlamps are activated when the light control switch is in the headlamp position and the ignition is in
position II.
High Beam Headlamps
The main beam headlamps are activated when the light control switch is in the headlamp position and the ignition is
in position I or II. Moving the column switch forwards from the low beam position activates the main beam headlamps.
When the ignition is in position I or II and the column switch is moved rearwards to the headlamp flash position, the
main beam lamps are activated for as long as the switch is held in this position.
If the vehicle is involved in an accident and the airbags are deployed, the crash message from the DCU also
illuminates the main beam headlamps which flash at the same frequency as the hazard warning lamps.
The functionality of the main beam differs between halogen only and bi-xenon and halogen headlamps. This is shown
in the following table:
Xenon Headlamps
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. The
Xenon gas reacting to the controlled current flow between the electrodes produces the blue/white light.
To operate at full efficiency, the xenon bulb go through three phases of operation before full output for continuous
operation is achieved. The three phases are; starting phase, warm-up phase and continuous phase.
WARNING: The xenon system generates up to 28000 volts and contact with this voltage could lead to fatality.
Make sure the headlamps are switched off before working on the system.
In the start-up phase the bulb requires an initial high voltage starting pulse of 18000 to 28000 volts to establish the
arc. This is produced by the igniters. The warm-up phase begins once the arc is established. The control modules
regulate the supply to the bulbs 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 stabilises ensuring a continual current flow between the
electrodes. When the warm-up phase is complete, the control modules change to continuous phase. The supply
voltage to the bulb is reduced and the operating power required for continual operation is reduced to 35W.
The xenon system is controlled by the LCM, two control modules and two igniters. The control modules (one per
headlamp) receive an operating voltage from the LCM when the headlamps are switched on. The control modules
regulate the power supply required through the phases of start-up. The control modules also have diagnostic
capability which can be accessed using TestBook/T4 via the diagnostic socket.
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 igniter
provide a closed circuit for regulated power supply from the control modules
Front Fog Lamps
The front fog lamps are only active with the ignition switch in position II and the light control switch in the side lamp or
headlamp position. When the ignition is switched off, the fog lamp selection is automatically deselected.
Light Control Switch Position
Halogen Main Beam Only
Bi-xenon and Halogen Main Beam
0
OFF
OFF
OFF
0 + flash
ON
OFF
ON
I
OFF
OFF
OFF
I = flash
ON
OFF
ON
II
OFF
OFF
OFF
II + flash
ON
OFF
ON
II + main
ON
ON
ON
Daylight running lamps (Canada only)
ON (5.5 to 6.0V)
OFF
ON (5.5 to 6.0V)