1999 LAND ROVER DISCOVERY warning lights

CONTENTS
26 CONTENTS
LIGHTING.................................................................................................. 86-2-1
ADJUSTMENTS
Headlamps beam alignment - up to 03MY ..................................................................................... 86-2-1
Headlamps beam alignment - from 03MY ...................................................................................... 86-2-2
REPAIRS
Lamp - front repeater - up to 03MY ................................................................................................ 86-2-3
Headlamp - up to 03MY .................................................................................................................. 86-2-4
Headlamp - from 03MY .................................................................................................................. 86-2-5
Lamp - tail ..................................................................................................................................... 86-2-6
Lamp - front fog up to 03MY ........................................................................................................... 86-2-6
Lamp - front fog from 03MY ............................................................................................................ 86-2-7
Housing - number plate lamp ......................................................................................................... 86-2-8
Motor - headlamp levelling ............................................................................................................ 86-2-9
Lamp - stop - centre high mounted (CHMSL) .............................................................................. 86-2-10
Lamp - tail/flasher - bumper ............................................................................................................ 86-2-10
Lamp - interior - front .................................................................................................................... 86-2-11
Lamp - interior - rear ..................................................................................................................... 86-2-11
Rheostat - panel lights dimmer ...................................................................................................... 86-2-12
Switch - hazard warning ................................................................................................................ 86-2-13
Switch - indicator and exterior lighting - combined ......................................................................... 86-2-13
Socket - accessory ........................................................................................................................ 86-2-14
Switch - front/rear fog lamps ......................................................................................................... 86-2-14
BODY CONTROL UNIT ............................................................................ 86-3-1
DESCRIPTION AND OPERATION
Description ...................................................................................................................................... 86-3-1
Operation ........................................................................................................................................ 86-3-19
REPAIRS
Body control unit (BCU) .................................................................................................................. 86-3-35
ALARM SYSTEM AND HORN.................................................................. 86-4-1
DESCRIPTION AND OPERATION
Alarm system component layout..................................................................................................... 86-4-2
Alarm system block diagram........................................................................................................... 86-4-4
Description ...................................................................................................................................... 86-4-5
Operation ........................................................................................................................................ 86-4-17
REPAIR
Switch - central door locking ......................................................................................................... 86-4-25
Switches - horn ............................................................................................................................. 86-4-25
Vehicle horn .................................................................................................................................. 86-4-26
Sounder - alarm ............................................................................................................................ 86-4-26
Sounder - battery backed-up (BBUS) ............................................................................................. 86-4-27
Switch - bonnet ............................................................................................................................. 86-4-27
Receiver - alarm system - models with sunroof ............................................................................. 86-4-28
Receiver - alarm system - models without sunroof ......................................................................... 86-4-28
Coil - passive immobilisation ........................................................................................................ 86-4-29

MAINTENANCE
PROCEDURES 10-5
Lamps, horns and warning indicators
Check
1.Switch on side, head and tail lamps and check
operation.
2.Check headlamp levelling operation.
3.Check turn signals and hazard warning lamps
for correct operation.
4.Press brake pedal and check operation of
brake lamps.
5.Check all exterior lamp lenses for clarity and
condition. Pay particular attention to headlamp
lenses for signs of stone chips or damage.
6.Check horn for loud, clear sound.
7.Switch on headlamps (with ignition switch at 'O'
position) and check light reminder warning
operates when door is opened.
8.Check operation of interior courtesy lights.
9.Check operation of all instrument pack warning
and indicator lights.
Wipers and washers
Check
1. Operate screen washer and switch on wipers.
Ensure washer jets are correctly aimed and
check for smooth, smear free operation of
wiper blades across screen at all speeds
including intermittent.
2.Repeat operation for rear screen washers/
wipers.
3.Check all wiper blades for condition and signs
of splits or damage.
4.Check security of wiper arms.

AIR CONDITIONING
82-14DESCRIPTION AND OPERATION
Display outputs
1LH temperature
2Economy mode
3Recirculated air
4Automatic mode5Manual distribution
6RH temperature
7Blower speed
8External air temperature
Outputs on the display are shown at full brightness when the exterior lights are off, and dimmed when the exterior
lights are on.
LH temperature. Illuminates to show the LH temperature selection, the temperature scale or that the ATC ECU is in
diagnostic mode.
Economy mode. Illuminates when the compressor is manually selected off with the ECON switch.
Recirculated air. Illuminates when the inlet air is manually selected to recirculated mode.
Automatic mode. Illuminates the AUTO legend and related symbol(s) when the blower speed, air distribution or
temperature control are in the automatic mode.
Manual distribution. Illuminates the appropriate symbol(s) to show the manually selected air distribution. Also
illuminates in the automatic modes when one of the temperatures is set to LO or HI.
RH temperature. Illuminates to show the RH temperature selection, external air temperature or diagnostic fault code.
Blower speed. Illuminates when the blower speed is manually selected. Also illuminates in the automatic modes when
one of the temperatures is set to LO or HI.
External air temperature. EXT illuminates to show that external air temperature is selected on.
All temperature indications on the display are in either °C or °F. For 1 second after the system is first switched on, the
display shows only °C or °F, in the LH temperature window, to indicate which temperature scale is in use. After 1
second, the °C or °F indication goes off and the display shows all relevant outputs.
Temperature conversion: While the system is on, the temperature indications on the display can be switched between
the two scales by pressing and holding the fresh/recirculated air switch, then pressing and holding the A/C on/off
switch until the audible warning sounds (approximately 3 seconds).

BODY CONTROL UNIT
DESCRIPTION AND OPERATION 86-3-11
Programmable options
The BCU can be programmed with a number of options to satisfy specific market requirements and customer
preferences. The options can be set using TestBook.
Function Option Details
Transmission Manual The vehicle is fitted with manual transmission.
Automatic The vehicle is fitted with automatic transmission.
Front fog lamps None The vehicle is not fitted with front fog lamps.
Main The front fog lamps will operate if the headlamps are on main beam.
No main The front fog lamps will not operate if the headlamps are on main
beam.
Interlocks None The vehicle is not fitted with key, shift or transfer box interlocks.
Shift The vehicle is fitted with key, shift and transfer box interlocks.
No transfer The vehicle is fitted with key and shift interlocks, but not a transfer box
interlock.
Daylight running lamps None The vehicle is not fitted with daylight running lamps.
No main The daylight running lamps are on if the headlamp main beams are off.
No heads The daylight running lights are on with headlamp main and dipped
beams off and the gearbox not in Park.
Programmed wash/ wipe Normal The front wipers operate if the front wash is operated.
No wipe The front wipers do not operate if the front wash is operated.
Key-in warning Disabled The ignition key in audible warning is disabled.
Enabled The ignition key in audible warning is generated if the ignition key is in
and the driver's door is open.
Electric front seats None The vehicle is not fitted with electric front seats.
Normal Electric seat adjustment is available for 45 seconds after the driver's
door opens or if the ignition is on.
Ignition II Electric seat adjustment is available if the ignition is on.
Electric front windows Driver cancel The front windows will be disabled 44 seconds after the driver's door
is opened.
All cancel The front windows will be disabled 44 seconds after any door is
opened.
No cancel The front windows will be disabled when the ignition is turned off.
Heated front screen Fitted The vehicle is fitted with heated front screens.
None The vehicle is not fitted with heated front screens.
Rear windows and sunroof Driver cancel The rear windows and sunroof will be disabled 44 seconds after the
driver's door is opened.
All cancel The rear windows and sunroof will be disabled 44 seconds after any
door is opened.
No cancel The rear windows and sunroof will be disabled when the ignition
switch is turned off.
Gear position indicator
illuminationAlways The automatic gearbox selector illumination is on when the ignition is
on.
Sidelights The automatic gearbox selector illumination is on when the ignition is
on and the sidelights are off.
Hill descent control None The vehicle is not fitted with hill descent control.
Fitted The vehicle is fitted with hill descent control.
Courtesy headlamps Disabled The vehicle is not fitted with courtesy headlamps.
Enabled The vehicle is fitted with courtesy headlamps.
Odometer error warning Disabled The odometer will not flash if there is an odometer error.
Enabled The odometer will flash if there is an odometer error.

BODY CONTROL UNIT
86-3-18 DESCRIPTION AND OPERATION
Audible warnings
The BCU can request the instrument pack to generate an audible warning in response to conditions it has detected
and which need to be drawn to the driver's attention. One of six different audible warnings can be requested by the
BCU.
Sound request number Sound functions Priority (1 = lowest, 6 = highest)
0Off 1
1 Seat belt warning 6
2Key-in warning 3
3 SLABS/ HDC warning 4
4 Transfer box in neutral warning 5
5 Lights on warning 2

BODY CONTROL UNIT
86-3-28 DESCRIPTION AND OPERATION
Courtesy headlamps
This feature activates the headlamps for 30 seconds when the lock button on the remote transmitter is held down for
longer than 1 second. The headlamps will extinguish if the BCU receives either a lock or an unlock signal from the
remote transmitter.
The BCU checks the status of the following inputs to determine the correct qualifying conditions for requesting
courtesy headlamps:
lIgnition state.
lRemote locking request.
lRemote unlocking request.
lLazy locking request.
If the ignition is off and a lazy locking request is received, the courtesy headlamps are switched on and an internal
timer is turned on in the BCU which operates for 30 seconds. If the 30 second timer expires or a request for remote
locking or remote unlocking is received, the courtesy headlamps will be turned off.
When main beam is selected, the IDM also provides a signal to the instrument pack to switch on the main beam
warning lamp. An additional signal 'main beam indicator disable' is used to prevent the daylight running lamps
illuminating the main beam indicator when the main beam is in the daylight running lamp state and the main beam
indicator disable signal is on.
Lights on alarm
The lights on alarm in the instrument pack operates when the driver's door is open and the side lamps or headlamps
are on. The system uses inputs from the driver's door switch and the lighting switch to determine the logical conditions
that need to occur for switching on the alarm. The BCU carries out the logic operation and communicates with the
instrument pack using the serial data bus; the instrument pack will be requested to sound the alarm if the logic inputs
indicate that the driver's door is open with the lights still on.
Supply voltage is provided through the lighting switch to the IDM which acts as the signal line to indicate that the lights
are on for the logic circuits in the IDM and BCU. When the driver's door is opened, a second feed is supplied to the
BCU through the driver's door switch to indicate the condition. In this logic condition (lights on and driver's door open)
the BCU signals the instrument pack to operate the audible warning. If the lights are switched off or the driver's door
is closed the logic condition will be changed and the audible warning will be switched off.
Daylight running lamps
The BCU operates the daylight running lamps (where fitted) via the IDM. The daylight running lamps option can be
programmed in one of three states dependent on market/ customer requirements, these are:
lOption 1– no daylight running lamps.
lOption 2 – on with main beam off.
lOption 3 – on with main and dipped beam off and gearbox not in Park.
The BCU will ensure the logical conditions are satisfied for the lamps to operate under the set conditions. The BCU
checks the status of the following inputs to determine the logic action for providing an output to the daylight running
lamp relay:
lMain beam state.
lEngine running (link from instrument pack).
lDipped beam.
lGearbox state.
A voltage supply is fed to the coil of the daylight running lamp relay and the IDM. When the preconditions are satisfied
for daylight running lamp operation, the BCU sends a signal for the IDM to complete the circuit to earth to switch on
the daylight running lamps. The logical inputs are checked to ensure that the engine is running before switching the
relay to turn on the daylight running lamps. The engine running signal has to be present for at least 2 seconds before
the daylight running lamp relay can be switched on.
Fog lamps
The BCU operates the rear fog lamps and the front fog lamps (where fitted) via the IDM. The BCU front fog lamp
operation can be programmed to operate under one of three set conditions. The BCU will ensure the logical conditions
are satisfied for the lamps to operate under the set conditions.

BODY CONTROL UNIT
86-3-30 DESCRIPTION AND OPERATION
Interior courtesy lamps
To determine when to provide an interior courtesy lamps enable output, the BCU checks the following input
conditions:
lIgnition state.
lTransit mode.
lDriver's door open.
lPassenger or rear door open.
The courtesy lamps operate at full brightness when they are first switched on. The BCU then gradually dims the lamps
(fade-out) before completely switching them off. Fade-out occurs over a period of two seconds following the logical
control signal to turn off the lights. When a door is opened, the BCU provides earth paths from the interior lamps, the
load space lamp and the ignition switch illumination. The following table lists the courtesy lamps operation and
duration for holding the lamps on that occurs after the BCU has detected a condition that signals the courtesy lamps
should be switched on:
Instrument pack
The BCU communicates with the instrument pack to provide a range of functions.
Odometer update
The BCU can be programmed for one of two options:
lOption 1 – no odometer error warning.
lOption 2 – odometer error warning.
In order to provide an LCD flash request to the instrument pack via the communications link, the following inputs are
checked:
lIgnition state.
lInstrument pack odometer value (via the communications link).
lBCU odometer value.
The function is only active when the ignition state is on. The maximum allowed value is 999,999 miles (1,608,999
km).If the instrument pack odometer value is greater than the maximum allowed value, the maximum value is
assumed. The BCU odometer value is stored in EEPROM. If 16 identical values of the instrument pack odometer
reading is received consecutively, the instrument pack odometer value is compared with the BCU odometer value. If
the consecutive readings from the instrument pack differ, the BCU odometer value is incremented accordingly. If the
BCU odometer value is less than the instrument pack odometer value by up to 10 km, the BCU odometer value is set
equal to the instrument pack odometer value.
If the odometer warning option is enabled, and the contents of the instrument pack odometer value buffer is identical
to, or greater than BCU odometer value ± 10 km, the BCU sends an LED flash request to the instrument pack.
In the event of a communications link failure, this function will be unable to operate.
Control signal Additional conditions Duration
Door open - 10 minutes
Unlock signal from remote transmitter All doors closed and ignition switch not in
position III1 minute
Unlock signal from the driver's door lock All doors closed and ignition switch not in
position III1 minute
Ignition switch turned from position II or III to
position 0All doors closed 1 minute
Door changed from open to closed All other doors closed and ignition switch not
in position III15 seconds
Ignition switch in position III - Timer cancelled
BCU receives a lock command - Timer cancelled
Vehicle has transit mode enabled - 15 seconds on all occasions

BODY CONTROL UNIT
86-3-34 DESCRIPTION AND OPERATION
Key-in warning
The BCU can be programmed to one of two options:
lOption 1 – no timeout.
lOption 2 – no key-in warning.
The BCU issues an audible warning No. 2 request, depending on the status of the following inputs:
lIgnition state.
lIgnition key inserted.
lDriver's door open.
If the key-in warning is programmed into the BCU for operation, audible warning No.2 will be requested if the ignition
switch is off, the ignition key inserted signal is on and the driver's door open signal is ON.
In the event of a communications link failure occurring, the audible warning request is not sent to the instrument pack.
SLABS HDC warning
The BCU issues an audible warning No. 3 request, depending on the status of the following inputs:
lIgnition state.
lSLABS HDC warning.
The SLABS warning transmitted by the SLABS ECU is a 2 Hz signal, audible warning No. 3 is requested on every
falling edge of this signal. If the signal from the SLABS ECU stays low for more than 650 ms, audible warning No. 3
is requested every 2 seconds, for 30 seconds, while the signal stays low.
In the event of a communications link failure occurring, the audible warning request is not sent to the instrument pack.
Transfer box in neutral warning
If the transfer box is in the neutral position and the ignition switch is on, the BCU issues an audible warning No. 4
request. The BCU checks for the following inputs:
lTransfer box neutral selected.
lIgnition on.
The transfer box in neutral warning is activated by communicating with the instrument pack via the serial datalink. If
a communications link failure occurs while the transfer box in neutral warning is active, the audible warning will not
operate.
Lights on warning
If the ignition switch is off while the side lamps or headlamps on and the driver's door is opened, the BCU issues an
audible warning No. 5 request.
The BCU checks for the following inputs:
lDriver's door open.
lIgnition on.
lSide lamps.
lDipped beam state.
lMain beam state.
The lights on warning is activated by communicating with the instrument pack via the serial datalink. If a
communications link failure occurs while the lights on warning is active, the audible warning will not operate.
SLABS raise/lower
Before enabling a SLS vehicle raise/ lower request, the BCU checks the logical condition of the following inputs:
lIgnition state.
lSLABS raise request.
lSLABS lower request.
If the ignition switch is in position 0 or I, the vehicle raise/ lower request is off.
With the ignition switch in position II, and the 'SLABS raise' request and 'SLABS lower' request both off, the vehicle
raise/ lower request output is driven at 25 Hz with a 50% duty cycle and the vehicle height remains unchanged.
If the 'SLABS lower' request input is on, the vehicle raise/lower request output is driven at 25 Hz with a 25% duty cycle,
lowering the vehicle.
If the 'SLABS raise' request input is on, the vehicle raise/lower request output is driven at a 25 Hz with a 75% duty
cycle.