Window LAND ROVER DISCOVERY 1999 Owner's Manual

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).

AIR CONDITIONING
82-16DESCRIPTION AND OPERATION
Operation
General
While the system is on, the ATC ECU operates the refrigerant system and the inlet air, blower speed, air temperature
and air distribution functions to produce the conditions requested on the control panel. When the system is first
switched on, the ATC ECU resumes the control outputs in use when the system was last switched off. If conditions
have changed, or a different mode is selected to switch the system on, the control outputs are then changed to
produce the required new settings.
The system operates in automatic, economy and defrost modes, with manual overrides of the inlet air source, blower
speed and air distribution. The air temperature is automatically controlled in all operating modes.
In the automatic mode, the ATC ECU operates the system to warm-up or cool down the cabin to establish and
maintain the temperature selections on the control panel, while directing the air to those outlets most comfortable for
the occupant(s). If a difference between the LH and RH temperature selections causes a conflict of the required inlet
air source, blower speed or air distribution settings, priority is given to achieving the temperature requested on the
driver's side of the control panel.
The ATC ECU enters the economy mode when the refrigerant compressor is selected off while the system is in the
automatic mode, which reduces the load on the engine. Economy mode operation is similar to the automatic mode,
but without the ability to cool the cabin if the ambient temperature is higher than the temperature selections made on
the control panel, or to dehumidify the air in the cabin.
In the defrost mode, the ATC ECU sets the inlet air source to fresh air, the blower to maximum speed, the air
distribution to windscreen and side windows, and outputs signals to the BCU to operate the rear window heater and
(where fitted) the windscreen heater. The BCU starts or, if the heaters are already on, resets the heater timers and
energises the rear window and windscreen heaters for a complete on cycle.
Air temperature control
To determine the amount of heat or cooling required by the cabin, the ATC ECU uses the sensor inputs and the
temperatures selected on the control panel to calculate target air outlet temperatures for the driver's and the front
passenger's side of the heater assembly. The ATC ECU then signals the servo motors controlling the respective blend
flaps in the heater assembly to move to the flaps to the appropriate position. The target temperatures are constantly
updated and, in the automatic mode, also used in further calculations to determine the inlet air source, the blower
speed and the air distribution.
Inlet air control
The inlet air source is automatically controlled while the system is off or on. While the system is on, the inlet air source
can also be manually controlled to give timed recirculated air or latched recirculated air.
While the system is off, the ATC ECU uses vehicle speed to determine the inlet air source. With the vehicle at rest,
the inlet air source is set to recirculated air. When vehicle speed reaches 17.5 mph (28 km/h), the inlet air source
changes to fresh air. The inlet air source then remains at fresh air until the vehicle speed decreases to 5 mph (8 km/
h), when it returns to recirculated air.
While the system is on, the ATC ECU uses the LH and RH temperature selections, vehicle speed, ambient air
temperature and coolant temperature to determine the inlet air source. In the automatic mode:
lIf one temperature selection is set to LO and one is set to a specific temperature or HI, the inlet air is set to
recirculated air.
lIf one temperature selection is set to HI and one is set to a specific temperature or HI, the inlet air is set to fresh
air.
lWhen specific LH and RH temperature selections are set, the inlet air source remains at fresh air except when
the air distribution function is set to face level only or face level and footwell outlets. If the air distribution function
is set to face level only or face level and footwell outlets, at 56 mph (90 km/h) the inlet air source changes to
recirculated air (to exclude ram effect, which becomes excessive at speed). When the vehicle speed decreases
to 37.5 mph (60 km/h), the inlet air source returns to fresh air.
In the defrost mode, the inlet air source is set to fresh air except at low ambient air and coolant temperatures. If, within
5 minutes of the ignition being switched on, the vehicle speed is less than 5 mph (8 km/h) while the external air
temperature is −16 °C (3 °F) or less and the heater coolant temperature is −10 °C (14 °F) or less, then the inlet air
source is automatically set to the timed recirculated air mode. The timed recirculated air mode is cancelled
immediately the vehicle speed reaches 8 km/h or more .

AIR CONDITIONING
DESCRIPTION AND OPERATION 82-19
Diagnostics
The ATC ECU performs a diagnostic check each time the ignition is switched on. To avoid nuisance fault indications
at low light levels, the sunlight sensor is omitted from the diagnostic check. If a fault is detected, the audible warning
sounds three times and the AUTO window on the control panel display flashes for 20 seconds. The ATC ECU then
reverts to normal control but uses a default value or strategy for the detected fault. Faults are identified by performing
a manual diagnostic check of the system.
A manual diagnostic check includes a check of the sunlight sensor, and is initiated by pressing and holding the AUTO
switch and the air distribution switch, then turning the ignition switch from off to on. The audible warning sounds once
and the indications on the control panel display illuminate. FC is shown in the LH temperature window and the results
of the check are shown as a two digit fault code in the RH temperature window. If a fault is detected, the audible
warning sounds three times and the AUTO window on the display flashes on and off for 20 seconds. If more than one
fault is detected, the fault codes cycle in numerical order, at 1 Hz. The audible warning sounds as each fault code is
shown. In low light conditions, to avoid false sunlight sensor fault indications, the sunlight sensor should be illuminated
with a strong light source.
Diagnostic fault codes and fault descriptions
Code Component Fault Default value/strategy
00 - No fault found -
11 In-car temperature sensor Open or short circuit 25°C (77°F)
12 Ambient temperature sensor Open or short circuit 10°C (50°F)
Cooling fan permanently on
Display shows "- -" if external air
temperature selected
13 Thermistor Open or short circuit 0°C (32°F)
14 Heater coolant temperature sensor Open or short circuit 70°C (158°F)
21 Sunlight sensor, left output Open or short circuit No solar heating correction
22 Sunlight sensor, right output Open or short circuit No solar heating correction
31 LH temperature servo motor Open or short circuit
Motor or flap mechanism seizedServo motor locked in position
32 RH temperature servo motor Open or short circuit
Motor or flap mechanism seizedServo motor locked in position
33 Distribution servo motor Open or short circuit
Motor or flap mechanism seizedServo motor locked in position

WIPERS AND WASHERS
DESCRIPTION AND OPERATION 84-5
1Windscreen washer jet 2 off
2Elbow 3 off
3In-line non-return valve
4Tube
5'T' connector
6Tube
7Connector
8Filler neck tube
9Filter
10Cap
11Bracket
12Level float
13Filler neck seal
14Bolt
15Reservoir
16Pump sealing grommet (if fitted)
17Powerwash pump (if fitted)18Clip
19Tube
20Screw 2 off
21Powerwash jet 2 off
22Clip 4 off
23Tube
24'T' connector
25Tube
26Nut 2 off
27Pump sealing grommet 2 off
28Rear washer pump
29Front windscreen washer pump
30Elbow 2 off
31Tube - front windscreen
32Tube - rear tail door window
33Non-return valve

WIPERS AND WASHERS
84-12 DESCRIPTION AND OPERATION
Rear wiper
The rear wiper is driven directly from an electric motor located inside the tail door. The motor is mounted inside the
tail door with two bolts, lock washers and washers. The motor mounting brackets have rubber inserts to prevent motor
operating noise being transferred to the door structure. The motor spindle is fitted with a seal and protrudes through
a hole in the tail door outer skin panel. The motor spindle is secured to the tail door with a washer and nut.
The motor output spindle has a taper splined shaft which allows for the attachment of the wiper arm which is secured
with a nut. The wiper arm attachment to the splined shaft has a pivot to which the remainder of the arm is attached.
The two parts of the arm are connected by a spring which controls the pressure of the blade on the window to a
predetermined amount.
The wiper blade is attached to the wiper arms with a clip which allows the blade to pivot. The wiper blade comprises
of a number of levers and yokes to which the rubber wiper is attached. The levers and yokes ensure that the pressure
applied by the arm spring is evenly distributed along the full length of the blade. The rubber wiper is held in the yokes
by a pair of stainless steel strips which also contribute to the even distribution of spring pressure along the blade.
Rear wiper switch
The rear wiper switch is a latching pushbutton switch and is located on the right hand side of the instrument pack.
Activating the rear wiper switch provides an earth signal to the BCU. The BCU signals the IDM to energise the rear
wiper relay, which provides battery voltage to the rear wiper motor.

WIPERS AND WASHERS
DESCRIPTION AND OPERATION 84-13
Rear wiper motor
The DC motor contains two permanent magnets and a park switch. An earth braid attached between the motor casing
and the brush pack is utilised to minimise radio interference during wiper functions.
The rear wiper switch provides an earth signal to the BCU, which determines the delay interval, if appropriate. The
BCU then signals the IDM to activate the rear wiper motor relay, which provides power to the rear wiper motor.
To allow the rear wiper to park when the rear wiper is switched off, power flows through the park switch until a cam
in the wiper motor assembly breaks the contact of the park switch. Triggering the park switch grounds the positive
side of the wiper motor causing it to stop abruptly
Washers
The washer system comprises a reservoir, washer pumps, hoses and washer jets. The front washers are controlled
from a stalk switch on the steering column and the rear washers are operated by a non-latching pushbutton switch on
the fascia adjacent to the instrument pack.
Reservoir
The reservoir is located behind the front bumper in the inner wheel arch and has a capacity of 6.0 litres (12.5 US pints).
A filler neck tube is connected to the reservoir with a seal and extends into the engine compartment on the front left
hand side. The filler neck tube contains a removable filter to prevent particle contamination and a yellow float to show
reservoir contents. The washer filler neck tube is sealed with a cap which is coloured blue for identification.
Two electric washer pumps are located on the rear face of the reservoir and supply washer fluid to the front
windscreen and the tail door window. Each pump is sealed to the reservoir with a rubber sealing grommet.
On vehicles with headlamp powerwash fitted, a third pump is fitted with a sealing grommet to the front face of the
reservoir.
The reservoir and filler neck tube are manufactured from moulded opaque nylon. The reservoir has moulded lugs for
attachment to the vehicle body. A bracket is attached to the top of the filler neck tube and locates in a hole in the body
to secure the top of the tube.
Front screen washer jets
Two washer jets for the front windscreen are fitted to the top surface of the bonnet and held in place with plastic clips.
Each washer jet is connected via a hose to an in-line valve. The in-line valve prevents the washer fluid draining back
to the reservoir and ensures that the washers operate immediately the washer pump is operated. From each in-line
valve the washers are connected via a short hose to a 'T' connector. From the 'T' connector a single hose connects
to the outlet of the front washer pump. Each jet has two jets which can be adjusted to allow full fluid coverage of the
windscreen.

WIPERS AND WASHERS
84-14 DESCRIPTION AND OPERATION
Rear screen washer jet
A single washer jet for the tail door window is fitted to the rear wiper blade. The jet has four spray orifices which direct
washer fluid to either side and along the length of the wiper blade. The jet is connected by a hose from the wiper blade,
through a sealing grommet in the tail door and connects with the rear washer hose from the rear washer pump. A non-
return valve is used to join the feed hose from the pump to the washer jet hose. The non-return valve prevents fluid
draining to the reservoir and ensures that the washer operates immediately the washer pump is operated. The hose
from the pump to the tail door is located inside the main harness.
Headlamp power washer jets
When fitted, a powerwash jet for each headlamp is located in a housing on the top surface of the front bumper. The
jets are fed with fluid at high pressure from the powerwash pump. A large diameter hose connects each jet to the
pump. Each connection is secured with a metal clip to secure the hose due to the high pressure from the pump. Each
jet directs the high pressure fluid in a wide spray onto the headlamp lens.
Rear washer switch
The rear washer switch is a non-latching pushbutton switch and is located on the RH side of the instrument pack.
Activating the rear washer switch provides battery voltage from fuse 30 in the passenger compartment fusebox to the
rear washer pump.

BODY CONTROL UNIT
DESCRIPTION AND OPERATION 86-3-1
BODY CONTROL UNIT DESCRIPTION AND OPERAT ION
Description
General
The Body Control Unit (BCU) is located behind the passenger glovebox and is connected to the main harness by four
connectors on its bottom edge and an additional connector located on the side of the BCU casing. Mounting the BCU
behind the fascia makes it reasonably inaccessible for intruders to disable the anti-theft system.
The BCU uses solid-state microprocessor control to perform logical operations and timing functions for a variety of
the vehicle's electrically operated systems, these include:
lDoor locking.
lAnti-theft alarm and immobilisation system.
lExterior lighting including direction indicators and hazard warning lamps.
lCourtesy lighting.
lWipers and washers.
lElectric windows and sunroof.
lHeated windows.
The BCU also communicates with several other electronically controlled systems such as the EAT ECU and SLABS
ECU and also has a datalink between the Intelligent Driver Module (IDM) and the instrument pack. The datalink is a
low speed bus capable of transmitting and receiving messages at a data rate of 10,400 bits per second. Additional
inputs and outputs to peripheral devices are included which are necessary for determining vehicle status for particular
logical operations e.g. crank, ignition key inserted, fuel flap enable etc.
The BCU receives its power supply from the engine compartment fuse box, and is protected by a 10 A fuse.
The BCU communicates with the IDM to provide the control signals to perform power switching operations in
conjunction with dedicated relays.
IDM
The IDM is integrated into the passenger compartment fuse box, which is mounted behind the fascia below the
steering column. There are no harnesses between the fuse box and the IDM. The IDM performs the power switching
operations for several of the vehicle's electrical systems.
The IDM communicates with the BCU and the instrument pack via a serial interface. If the BCU or the IDM is replaced,
the communications link between the two units has to be re-established. This can be done either by switching on the
ignition and leaving it on for five minutes, or by using TestBook. The vehicle immobilisation will remain active until the
communications link between the BCU and IDM has been re-established.
Transit mode
To prevent excessive battery drain during transit to overseas markets, the vehicle is placed in a transit mode. The
following functions are disabled when the vehicle is in transit mode:
lVolumetric sensors.
lPassive immobilisation.
lImmobilisation of the vehicle by use of door lock.
lIgnition key interlock.
lElectric seat enable time-out with driver's door open.

BODY CONTROL UNIT
86-3-2 DESCRIPTION AND OPERATION
Power supply
Battery supply to the BCU and the IDM is provided through a 10 A fuse located in the engine compartment fuse box.
The BCU unit receives an ignition switched power supply (ignition switch position II) input via a 10 A fuse in the
passenger compartment fuse box.
The BCU receives a signal when the ignition switch is turned to the crank position, it then supplies an earth path to
the starter relay coil, to enable the crank operation by supplying power through the starter relay contacts to the starter
motor.
Battery voltage is monitored and BCU operation will function normally between 8 and 18 volts. Between 5.7 and 8
volts the BCU is in the 'under volts' state. The status of the battery is used to determine which outputs may be driven.
If a voltage supply above 18 volts is experienced, outputs will not normally be driven except for those functions which
are required during cranking (robust immobilisation, antenna coil, crank enable relay and feed to gear position switch
contacts W, X, Y, Z). In the over voltage state the vehicle can be driven, but all other functions are disabled and
outputs are switched off (power windows, heated screen, direction indicators etc.).
All functions are disabled on power up until communications between the BCU and IDM have been established. If
communications cannot be established, operation will commence with degraded functionality.
Battery supply to the IDM is provided through the inertia switch and a 10 A fuse in the engine compartment fuse box.
If the inertia switch contacts are closed battery voltage is available at the IDM; if the inertia switch contacts are open
there is no battery supply to the IDM. The supply condition of the IDM is signalled to the BCU via the serial bus. If the
inertia switch is operated (contacts open) the change in state is detected by the BCU which unlocks the doors if the
ignition switch is in position II and the alarm is not set.
The BCU is earthed through a hard-wire connection.
Inputs and outputs
The BCU and IDM process inputs and provide the necessary outputs for control and operation of the vehicle's 'body'
systems.
BCU inputs
The BCU processes signals received from the following components:
lDoor latch switches.
lDriver's door key lock/ unlock switches.
lBonnet activated security system.
lVolumetric sensors.
lCentral Door Locking (CDL) switches.
lRemote transmitter (via receiver unit).
lInertia fuel cut-off switch.
lIgnition switch.
lFuel flap release switch.
The input voltages (V
in) for BCU digital signals are defined as follows:
lLogic 1 when V
in ≥ 6V.
lLogic 0 when V
in ≤ 2V.
BCU input voltages between 2 and 6 volts are indeterminate and cannot be guaranteed.
Analogue input voltages are measured as a ratio with respect to battery voltage.

BODY CONTROL UNIT
86-3-4 DESCRIPTION AND OPERATION
C0660 connector pin details
Pin No. Description Input/Output
1 Ignition power supply Input
2 Right front window - down Input
3 Auxiliary power supply Input
4 Passenger or rear door open Input
5 Driver's door key lock Input
6 RH indicator selected Input
7 Front fog lamps selected Input
8 Gear position feedback 'R' Output
9 Gear position feedback 'P' Output
10 SLS too high (audible warning) Input
11 Earth -
12 Vehicle raise/lower request Output
13 Battery power supply Input
14 Heated front screen selected Input
15 Bonnet open Input
16 CDL doors lock Input
17 Driver's door open Input
18 Left front window up Input
19 Right front window up Input
20 Rear washer pump Input
21 Front intermittent wiper switch Input
22 Gear position feedback '1' Output
23 Gear position feedback '2' Output
24 Gear position feedback '3' Output
25 Gear position feedback 'D' Output
26 Gear position feedback 'N' Output