Gear ratio LAND ROVER DISCOVERY 1999 Workshop Manual

BRAKES
DESCRIPTION AND OPERATION 70-3
1ABS sensor
2ABS modulator
3Return pump relay
4SLABS ECU
5Brake lamp relay
6Centre high mounted stop lamp
7LH brake lamp
8RH brake lamp
9Instrument pack10Body control unit
11Reverse lamp switch (manual gearbox)
12Diagnostic socket
13HDC switch
14Transmission high/low switch
15Centre differential lock switch
16Engine control module
17Battery power supply
18Ignition power supply

BRAKES
DESCRIPTION AND OPERATION 70-17
SLABS ECU
The SLABS ECU is attached to a bracket behind the front passenger glovebox. Brake related inputs are processed
by the SLABS ECU, which then outputs control signals to the ABS modulator. Five electrical connectors interface the
SLABS ECU with the vehicle wiring.
SLABS ECU connector pin details
Connector/Pin
No.Description Input/Output
C0504
1 Battery supply Input
2 Ignition supply Input
3 Road speed Output
4 Rough road (V8 models only) Output
5 K line (diagnostics) Input/Output
7 Reverse gear Input
8 Return pump monitor Input
9 Brake warning lamp Output
10 Engine data (throttle position, torque, engine type, gearbox type) Input
11 Transfer box range Input
12 Earth-
13 ETC warning lamp Output
14 HDC switch Input
15 Neutral selected (automatic gearbox only) Input
16 HDC fault warning lamp Output
17 HDC information warning lamp Output
18 ABS warning lamp Output
C0505
1 Front left wheel speed Input
2 Front left wheel speed Input
3 Rear right wheel speed Input
4 Front right wheel speed Input
5 Front right wheel speed Input
6 Rear right wheel speed Input
7 Rear left wheel speed Input
8 Rear left wheel speed Input
C0506
1 Front left outlet solenoid valve Output
2 Front left inlet solenoid valve Output
3Earth-
4 Front right outlet solenoid valve Output

BRAKES
70-18 DESCRIPTION AND OPERATION
The SLABS ECU continually calculates vehicle speed using the wheel speed inputs from all four ABS sensors. The
calculated vehicle speed is then used as a reference against which individual wheel speeds are monitored for
unacceptable acceleration or deceleration. The ABS sensor inputs are also used by the SLABS ECU to detect vehicle
deceleration rate, vehicle cornering rate and rough terrain.
The engaged forward gear and (on manual gearbox models) the clutch status are computed from the engine data
input, the engine speed input and vehicle speed. Reverse gear status is provided by an input from the reverse lamp
switch (manual gearbox models) or the BCU (automatic gearbox models). On automatic models, the BCU also
provides the neutral selected input.
In addition to controlling the brake related functions, the SLABS ECU:
lControls the operation of the self levelling suspension (SLS) system (where fitted).

+ REAR SUSPENSION, DESCRIPTION AND OPERATION, Description.
lOn V8 models, outputs a rough road signal to the ECM when traversing rough terrain.
lOutputs a vehicle speed signal.
The vehicle speed signal is output to the following systems (where fitted):
lActive Cornering Enhancement.

+ FRONT SUSPENSION, DESCRIPTION AND OPERATION, Description - ACE.
lAir conditioning.

+ AIR CONDITIONING, DESCRIPTION AND OPERATION, Description.
lCruise control.

+ ENGINE MANAGEMENT SYSTEM - Td5, DESCRIPTION AND OPERATION, Description.

+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.
lEngine management.

+ ENGINE MANAGEMENT SYSTEM - Td5, DESCRIPTION AND OPERATION, Description.

+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.
lIn-car entertainment.

+ IN CAR ENTERTAINMENT, DESCRIPTION AND OPERATION, Description.
lInstrument pack.

+ INSTRUMENTS, DESCRIPTION AND OPERATION, Description.
5 Front right inlet solenoid valve Output
6 Shuttle valve switches Input
7 Rear left outlet solenoid valve Output
8 Rear left inlet solenoid valve Output
9 Centre differential lock switch Input
10 Rear right outlet solenoid valve Output
11 Rear right inlet solenoid valve Output
12 Brake lamp relay Output
15 Return pump relay Output
C0655
7 Audible warning Output
10 Engine speed Input
Connector and pins not listed are either not used or used by the self levelling suspension system.

+ REAR SUSPENSION, DESCRIPTION AND OPERATION, Description.
Connector/Pin
No.Description Input/Output

BRAKES
DESCRIPTION AND OPERATION 70-21
ETC
The ETC function uses brake intervention to prevent wheel spin and maintain even torque distribution to the wheels.
ETC is automatically enabled while the brakes are off at speeds up to 62.5 mph (100 km/h), and operates the brakes
either individually or in axle pairs:
lAt speeds up to 31.3 mph (50 km/h), ETC uses individual brake intervention to maintain even torque distribution
between wheels on the same axle.
lVehicles up to 03 model year – At speeds between 0 and 62.5 mph (0 and 100 km/h), ETC also uses brake
intervention in axle pairs to maintain even torque distribution between the front and rear axles. In effect, this mode
of operation replaces the centre differential lock of the transfer box which, although still incorporated, is non
operational under normal driving conditions.

+ TRANSFER BOX - LT230SE, DESCRIPTION AND OPERATION, Description. If the centre differential
lock is in the locked condition, the SLABS ECU illuminates the ABS and ETC warning lamps and inhibits the ETC
function (the ABS, EBD and HDC functions are retained, but at degraded performance levels).
lVehicles from 03 model year (with differential lock fitted) – At speeds between 0 and 62.5 mph (0 and 100
km/h), ETC uses brake intervention in axle pairs to maintain even torque distribution between the front and rear
axles. If the centre differential lock is in the locked condition, the differential lock warning lamp in the instrument
pack is illuminated. The ABS, EBD, ETC and HDC functions are retained, but with revised parameters to suit the
locked differential.
While the ETC function is enabled, if the SLABS ECU detects a wheel accelerating faster than the average, indicating
loss of traction, it operates the ABS modulator in the active braking mode. Depending on the vehicle speed, active
braking is employed for either the brake of the affected wheel or for both brakes on the affected axle, until all four
wheels are driven at approximately the same speed again. During active braking the SLABS ECU also illuminates the
ETC warning lamp, for a minimum of 2 seconds or for the duration that ETC is active. ETC operation is desensitised
during 'hard' cornering.
HDC
HDC uses brake intervention to provide a controlled descent ability in off road conditions when engine braking is
insufficient to maintain a comfortable speed. This allows the driver to leave HDC selected and to control the vehicle's
descent speed, down to the system's minimum target speed, using only the accelerator pedal. The HDC function is
selected on/off by a switch on the fascia. When selected on, HDC is enabled in all forward gears and reverse provided:
lVehicle speed is below 31.3 mph (50 km/h).
lThe transfer box is in low range.
lOn manual gearbox vehicles, the clutch is engaged.
When HDC is enabled, the HDC information warning lamp illuminates. If HDC is selected outside the above
conditions, the HDC information warning lamp flashes and the audible warning sounds continuously.
When HDC is enabled, the SLABS ECU calculates a target speed from the throttle position element of the engine data
input, and compares this with actual speed. If the actual speed is higher than the target speed, the SLABS ECU
operates the ABS modulator in the active braking mode to slow the vehicle down to the target speed. While the braking
force is being applied, the SLABS ECU also energizes the brake lamp relay to put the brake lamps on. Active braking
is discontinued while vehicle speed is below the target speed or if the foot brakes are applied. Applying the foot brakes
during active braking may result in a pulse through the brake pedal, which is normal.
During active braking, the brakes are operated predominantly on the wheels of the leading axle, but if that is not
sufficient to achieve the required deceleration the brakes of the trailing axle are also applied. The deceleration rate is
dependent on the speed differential between initial vehicle speed and the target speed. The deceleration rates are
relatively low at higher speed differentials, then progressively increase as vehicle speed approaches the target speed.
Anti-lock braking is also enabled during active braking, but at very low speeds some wheel lock can occur.
The target speed increases as the accelerator pedal is pressed, from a programmed minimum with the accelerator
pedal released, up to a maximum of 31.3 mph (50 km/h). For any given accelerator pedal position, while travelling
uphill or on level ground the target speed is always greater than the corresponding vehicle speed, which allows the
vehicle to be driven normally without HDC intervention. However, when travelling downhill, the gravitational effect on
the vehicle means that for any given accelerator pedal position the target speed is less than the corresponding vehicle
speed, and HDC intervenes to limit vehicle speed to the target speed.

BRAKES
70-22 DESCRIPTION AND OPERATION
Minimum target speed
The minimum target speed depends on which gear is engaged. Reduced minimum target speeds are employed for
some gears if rough terrain or sharp bends are encountered while already travelling at the normal minimum target
speed. If loss of traction makes it impossible to maintain the minimum target speed, the SLABS ECU temporarily
increases the minimum target speed to maintain stability, then restores the normal minimum target speed when
traction improves.
HDC minimum target speeds
Fade out
To provide a safe transition from active braking to brakes off, the SLABS ECU invokes a fade out strategy if it detects
any of the following during active braking:
lA system fault.
lThe conditions for HDC are no longer being met.
lPossible brake overheat.
The fade out strategy increases the target speed at a low constant acceleration rate, independent of actual throttle
position. This results in the braking effort being gradually reduced and then discontinued. The SLABS ECU operates
warning indications during fade out that are dependent on the cause.
Fade out warning indications
Clutch disengagement/neutral selection
During active braking, if the SLABS ECU detects the clutch is disengaged or neutral is selected, it flashes the HDC
information warning lamp and sounds the audible warning continuously to indicate that conditions for HDC are no
longer being met. Initially, the SLABS ECU also fixes the target speed to the applicable minimum target speed, but if
the condition continues for approximately 60 seconds the SLABS ECU invokes fade out.
Brake overheat prevention
To prevent the brakes overheating, the SLABS ECU monitors the amount of active braking employed and, from this,
estimates brake temperature. If the SLABS ECU estimates the brake temperature has exceeded a preset limit, it
flashes the HDC fault warning lamp and sounds the audible warning continuously, to indicate that HDC should be
deselected to allow the brakes to cool. If active braking continues and the SLABS ECU estimates that brake
temperature has increased to an unacceptable level, fade out is employed and HDC is disabled. After fade out, the
audible warning is discontinued but the HDC fault warning lamp continues to flash, while HDC is selected, until the
SLABS ECU estimates brake temperature to be at an acceptable level. This calculation continues even if the ignition
is turned off, so turning the ignition off and back on will not reduce the disabled time. When the SLABS ECU estimates
the brake temperature to be acceptable, it extinguishes the HDC fault warning lamp and illuminates the HDC
information warning lamp to indicate that HDC is re-enabled. The disabled time is dependent on vehicle speed; typical
times at constant vehicle speeds are as follows:
Gear Speed, mph (km/h)
Manual gearbox Automatic gearbox
Normal Reduced Normal Reduced
1 4.4 (7.0) 4.4 (7.0) 4.4 (7.0) 4.4 (7.0)
2 5.2 (8.3) 4.4 (7.0) 4.4 (7.0) 4.4 (7.0)
3 6.0 (9.6) 4.4 (7.0) 7.5 (12.0) 6.0 (9.6)
4 7.5 (12.0) 6.0 (9.6) 7.5 (12.0) 6.0 (9.6)
5 8.8 (14.0) 7.0 (11.2) - -
Reverse 3.5 (5.6) 3.5 (5.6) 3.5 (5.6) 3.5 (5.6)
Neutral or clutch
disengaged8.8 (14.0) Last off road speed 4.4 (7.0) 4.4 (7.0)
Cause Warning indication
HDC fault warning lamp HDC information
warning lampAudible warning
Fault detected On Flashes Continuous
HDC conditions not met Off Flashes Continuous
Brake overheat prevention Flashes Off Continuous

SEATS
76-5-4 DESCRIPTION AND OPERATION
Description - electric seats
General
All markets use the same electric seat system. Electically operated lumbar support is optional. The system consists
of an electrical sub-system and a mechanical sub-system.
The electrical sub-system consists of the following components:
lBCU.
lSeat power relays.
lSeat switch packs.
lSeat fore/ aft motors.
lSeat cushion front up/ down motors.
lSeat cushion rear up/ down motors.
lSeat squab motor.
lLumbar pump.
lLumbar deflate solenoid.
The mechanical sub-system consist of the following components:
lGear wheels.
lRack and pinion assemblies.
Seat power relay
Located beneath the seat, the seat power relay supplies battery voltage to the satellite fuse box. Operation of the
relays is controlled by the BCU.
Voltage to the seat power relays is from fuse 5 in the engine compartment fuse box. The BCU controls the earth for
the relay coils. Operating the seat power relays provides voltage to the satellite fuse box under each seat.
Satellite fuse box
Located beneath the seat, the satellite fuse box provides circuit protection for the wiring to the seat switches and
motors. It also protects the lumbar inflate and deflate circuits.
The seat power relay provides voltage directly to the 40A fuse in the satellite fuse box. Voltage from this fuse feeds
the seat switch pack. The 3A fuses in the satellite fuse box protect the wiring to the lumbar pump and lumbar deflate
solenoid. Voltage to the 3A fuses comes from the seat switch pack.

SEATS
76-5-8 DESCRIPTION AND OPERATION
Operation - electric seats
Seat power relay enable line
The BCU provides the seat power relays with an earth supply to the relay coil that enables the relay operation. When
this seat power relay enable line is active, the seat power relay energises allowing seat operation.
In order for the seat power relay to be active the BCU must detect either of the following condition options:
lIgnition switch in position II.
lIgnition switch in position II or driver's door within 45 seconds of opening.
Seat fore/ aft movement
When the cushion switch is operated and the seat power relay enable line is operating, power and earth are supplied
to the motor in the seat, allowing the seat to move forward or backward depending on switch position. The motor
drives a gear wheel along a gear rack connected to the seat base. Sliding the cushion switch forward causes the motor
to drive the seat forward. Sliding the cushion switch rearward reverses polarity of the voltage at the seat motor, driving
the seat rearward.
Seat cushion front up/ down movement
When the cushion switch is operated and the seat power relay enable line is operating, power and earth are supplied
to the motor in the seat, allowing the front of the seat cushion to move upward or downward depending on switch
position. The motor drives a gear wheel along a gear rack connected to the seat base. Sliding the front of the cushion
switch upward causes the motor to drive the seat upward. Sliding the front of the cushion switch downward reverses
polarity of the voltage at the seat motor driving the seat downward.
Seat cushion rear up/ down movement
When the cushion switch is operated and the seat power relay enable line is operating, power and earth are supplied
to the motor in the seat, allowing the seat to move upwards or downwards depending on switch position. The motor
drives a gear wheel along a gear rack connected to the seat base. Sliding the rear of the cushion switch upward
causes the motor to drive the seat upward. Sliding the rear of the cushion switch downward reverses polarity of the
voltage at the seat motor driving the seat downward.
Squab fore/ aft movement
When the squab switch is operated and the seat power relay enable line is operating, power and earth is supplied to
the motor in the squab, allowing the squab to move forward or backward depending on switch position. The motor
drives a gear wheel along a rotary gear rack connected to the squab. Sliding the squab switch forward causes the
motor to drive the squab forward. Sliding the squab switch rearward reverses polarity of the voltage at the seat motor
driving the squab rearward.
Lumbar inflate/ deflate
Sliding the squab switch upwards when the seat power relay enable line is operating applies voltage to the lumbar
pump. The lumbar pump inflates the lumbar bladder, increasing lumbar support. The lumbar pump and the normally
closed lumbar deflate solenoid hold the air in the bladder. Sliding the squab switch downwards applies voltage to the
deflate solenoid, venting the air in the lumbar bladder to atmosphere, decreasing lumbar support.
Diagnostics
TestBook can only verify that the seat power relay line is enabled. It cannot determine the status of the system or any
of the components.

SUNROOF
DESCRIPTION AND OPERATION 76-6-3
1Glass panel
2Nut - glass panel
3Frame - glass panel
4Bolt - glass panel
5Drive cables and lifting assembly
6Screw - glass panel frame
7Sunroof frame
8Sunroof blind
9Screw - sunroof frame10Drain tubes
11Screw - motor
12Motor and gearbox
13Spacer - manual sunroof regulator
14Regulator - manual sunroof
15Handle - manual sunroof
16Screw - manual sunroof regulator
17Screw - manual sunroof handle

WIPERS AND WASHERS
DESCRIPTION AND OPERATION 84-11
Front wiper motor assembly
The front wiper motor assembly is located on the bulkhead beneath the plenum.
The dc motor contains two permanent magnets, three brushes and a park switch. The smaller third brush is utilised
for high-speed operation. Attached to the brush pack are 3 capacitors, which minimise radio interference during wiper
operation. A thermal trip switch attached to the brush plate prevents thermal overload of the motor.
The motor incorporates a worm drive gear unit to transfer the rotary motion into a linear motion of the wiper linkage
assembly.
The front wiper motor receives battery voltage from fuse 19 of the passenger compartment fuse box. For low-speed
operation, including intermittent variable delay operation, the battery voltage to move the wiper motor from the park
position passes through the front wiper relay. When the park switch moves to the closed when operating position,
fuse 19 of the passenger compartment fuse box provides battery voltage directly to the wiper motor.
For high-speed operation, including flick wipe, fuse 19 in the passenger compartment fuse box provides the battery
voltage to move the wiper motor from the park position through the front wash/ wipe switch to the front wiper motor.
To achieve high-speed wiper operation, power is supplied to a third brush that provides a closer distance between the
motor poles. Because the poles of the motor are closer together, the motor operates faster.

WIPERS AND WASHERS
84-18 DESCRIPTION AND OPERATION
Front flick wipe
Flick wipe operation will only activate when the following conditions are met:
lIgnition switch is in position I or II.
lFront flick switch is operated.
Pressing the flick wipe switch operates the front wiper motor at high speed. The front wiper motor operates as long
as the flick switch is activated. Releasing the flick switch causes the front wiper motor to run through the park switch
circuitry. The park switch only permits low speed operation. Thus if the flick switch is pressed and immediately
released, the wipers operate at low speed.
Rear intermittent wipe variable delay
The rear intermittent wipe variable delay operation allows the driver to adjust the interval between wipes to suit local
conditions. Rear variable delay operation only activates if the following conditions are met:
lIgnition switch in position I or II.
lFront wash/ wipe switch on intermittent.
lRear wipe switch is operated.
The BCU determines the desired delay interval based on the setting of the variable delay switch. The rear wash/ wipe
delay is nominally twice as long as that of the front. This information passes from the IDM to the rear wiper relay and
activates the rear wiper motor.
If the delay duration is decreased during operation of the rear wiper, the wipers immediately operate once and the
delay cycle is reset.
If the delay duration is increased during operation of the rear wiper, the delay cycle is automatically increased by the
BCU.
Reverse wiping
Reverse wiping operates the rear wiper motor when reverse gear is selected. The transmission must be in reverse
for longer then 0.5 seconds before reversing wipe activates. Reversing wipe activates if the following conditions are
met:
lIgnition switch is in position II.
lReverse gear is selected.
lRear wiper or front wipers operating.
If the rear wiper is active in any mode when reverse gear is selected, the rear wiper activates for 4 second. After 4
seconds the rear wiper operates in a delay operation at the same delay interval set by the variable delay switch until
reverse gear is deselected.
If the front wipers are operating on either low or high speed when reverse gear is selected, the rear wiper activates
continuously until reverse gear is deselected.
In order to enable reversing wipe functions, the BCU utilises the reversing light switch located within the transmission
to determine when reverse gear has been selected.
If the front intermittent wipe is active when reverse gear is selected, the rear wiper completes 2 cycles before operating
at the same intermittent delay as the front wipers.
Rear wipe
Rear wipe operation will only activate when the following conditions are met:
lIgnition switch is in position II.
lRear wipe switch is operated.
Operating the rear wiper switch provides an earth input to the BCU. The BCU tells the IDM to activate the rear wiper
relay, which provides battery voltage to the wiper motor through the normally closed contacts of the park switch.