LR3/Disco 3
The control has three marked positions; 0 to 3. The rotary wheel moves in 8, half positions to give fine adjustment control
over the headlamp position. The positions relate to vehicle loading or driving conditions as follows: Position 0 is the
normal position for unladen driving. Positions 1 to 4 lower the headlamp beam to compensate for a drop in height of the
rear of the vehicle.
0 = Driver only or driver and front seat passenger
0.5 = Driver, front seat passenger and 3rd row seats occupied (7 seat models) or all seats occupied (5 seat)
models
1 = All seat occupied (7 seat models)
1.5 = All seats occupied and maximum rear axle loading
2 = Driver only and maximum rear axle loading
3 and 4 = Can be used under certain driving conditions, i.e. off-road
Dimmer Control
The dimmer control provides a Pulse Width Modulated (PWM) output to control the illumination brightness of the
instrument panel and other fascia illumination. The dimmer switch operates using a rotary thumbwheel which is connected
to a rheostat and a high side switch.
The rheostat is a variable resistor which provides a high or low resistance according to its set position. This output is
passed to a switchable capacitor or a high side switch. The high side switch uses the output from the rheostat to
determine the switching frequency of the capacitor which provides the PWM output of between 8 and 12V to determine
the brightness of the illumination.
Automatic Headlamps
Refer to Automatic Headlamps in this section.
HEADLAMP ASSEMBLY
Three types of headlamp are available; Halogen, Bi-Xenon or Adaptive Front lighting System (AFS). The headlamps
share a common, clear lens.
The headlamps are located behind the front carrier assembly. Each headlamp is secured to the front carrier assembly
with two locking plates. The locking plate slides in grooves in the rear of the headlamp and two holes in each plate locate
on pins on the carrier. Each locking plate is pressed down to lock the pins in the locking plate holes. The locking plates
allow removal of the headlamp from the carrier for bulb changing without the requirement for special tools.
The rear of the headlamp unit has removable access panels which allow access to the bulbs for replacement. A large
cover, which is rotated anti-clockwise to remove, allows access to the low/high beam bulb on both halogen and xenon
headlamps. Another removable cover provides access to the high beam only halogen bulb which is retained with a spring
clip. A smaller cover can also be rotated anti-clockwise to provide access to the turn signal lamp bulb. Below this cover is
a removable cover which provides access to the side lamp bulb, the cornering lamp/static bending lamp bulb and the side
marker lamp bulb on NAS models.
The headlamps have two adjustment screws on the rear which allow for the manual setting of the vertical and horizontal
alignment. On NAS vehicles the headlamp is regarded as Visual Optically Left (VOL) aiming. The adjustment screws have
to be turned equal amounts to maintain the correlation in the vertical axis only. There is no horizontal adjustment. Refer to
the Service Repair Procedures manual for headlamp alignment data.
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 Reference Library (ERL)
for pin details.
The low beam headlamps are switched on when the ignition switch is in the ignition position (II) and:
the lighting control switch is in the headlamp position
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 switch is in the ignition position (II) and:
