1999 LAND ROVER DISCOVERY differential

INSTRUMENTS
88-2 DESCRIPTION AND OPERATION
Instrument component location - Engine
compartment / underneath vehicle
1ECM (diesel models)
2Alternator
3Glow plugs
4Transmission temperature sensor
5Water in fuel filter sensor
6Fuel tank sender unit
7Differential lock switch – vehicles up to 03
model year8Differential lock switches – vehicles from 03
model year (where fitted)
9Parking brake switch
10Brake fluid level switch
11Oil pressure switch

INSTRUMENTS
88-4 DESCRIPTION AND OPERATION
Instrument block diagram
1Instrument pack
2ECM
3Brake fluid level switch
4Parking brake switch
5Oil pressure switch
6Alternator
7Fuel tank sender unit
8Water in fuel filter sensor
9Transmission temperature sensor
10Differential lock switch - vehicles up to 03
model year or Differential lock switches -
vehicles from 03 model year11Audible warning speaker
12SRS DCU
13SLABS ECU
14BCU
15ACE ECU
16EAT ECU
17Diagnostic connector
18Serial communications link

INSTRUMENTS
DESCRIPTION AND OPERATION 88-5
Description
General
The instrument pack consists of four analogue dials, four warning lamp packs and a Liquid Crystal Display (LCD)
odometer.
The four dials are used to indicate:
lRoad speed.
lEngine speed.
lFuel tank level.
lEngine coolant temperature.
The dials are driven by a microprocessor from information received from the serial communication link. Information
input is received as either:
lDigital.
lAnalogue.
lPulse train.
lPulse Width Modulation (PWM).
The LCD provides information for:
lOdometer.
lTrip distance.
lSelected gear (on vehicles fitted with an automatic gearbox).
A trip reset button is provided to zero the trip display, this button also allows the selection of "miles" or "kilometres"
for the display. A photocell controls the illumination of the LCD, maintaining contrast of the display during ambient light
changes.
Within the four warning lamp packs there are 28 lamps. A long life bulb illuminates the high beam warning lamp and
the rest of the warning lamps are illuminated by Light Emitting Diodes (LED's). All warning lamp legends are invisible
until lit. When lit the symbols are illuminated on a black background.
The warning lamps illuminate in one of four colours. The colour indicates the level of importance to the driver, as
follows:
lRed = warning.
lAmber = caution.
lGreen = system operative.
lBlue = main beam operative.
The first warning lamp pack is located in the top left-hand side of the instrument pack and contains the following
warning lamps:
lTraction control warning lamp.
lTransfer box in neutral warning lamp.
lDifferential lock warning lamp
lOverspeed warning lamp (activated for gulf market only).
lBrake system warning lamp.
lHill Descent Control (HDC) information warning lamp.
lMalfunction Indicator Lamp (MIL)/ SERVICE ENGINE SOON warning lamp.
The second warning lamp pack is located in the centre of the instrument pack and contains the following warning
lamps:
lDirection indicator warning lamps.
lHigh beam warning lamp.
lAnti-lock brake system warning lamp.

INSTRUMENTS
DESCRIPTION AND OPERATION 88-23
Differential lock warning lamp (If fitted)
The differential lock is a device used for rolling road testing only on vehicles up to 03 model year. On vehicles from
03 model year, the differential is a driver selectable option which can also be used for off road driving. Refer to the
service procedures for details of rolling road testing on vehicles up to and from 03 model year.
CAUTION: Engage the differential lock when testing the vehicle on a two wheel rolling road. The propeller
shaft connecting the axle not on the rolling road must also be removed.
Differential lock warning lamp – vehicles up to 03 model year
The differential lock warning lamp within the instrument pack utilises a red LED and a clear legend. When the
differential lock is engaged, using the lever on the side of the transfer box, the differential lock switch is operated and
the warning lamp is switched on providing the driver with a visible warning.
When the differential lock is engaged, the warning lamp will be illuminated continuously when the ignition switch is in
position II.
Differential lock warning lamp – vehicles from 03 model year
The differential lock warning lamp is located in the top left hand corner of the instrument pack and uses an amber LED
and a clear legend. When the differential lock is engaged, the warning lamp illuminates when the ignition is on to
provide a visual indication to the driver that the differential lock is engaged. The instrument pack, simultaneously emits
three audible warning chimes as a confirmation.
When the differential lock is disengaged, the warning lamp is extinguished and the instrument pack simultaneously
emits three audible warning chimes as a confirmation.
All vehicles
The power input for the LED is supplied by the instrument pack via fuse 13 in the engine compartment fusebox. The
differential lock switch or switches provide(s) the earth path illuminating the warning lamp.
The voltage on the differential lock switch or switches to instrument pack earth path produces the following warning
lamp functions:
l< 1.8 volts = warning lamp on.
l> 7.7 volts = warning lamp off.