brakes LAND ROVER DISCOVERY 1999 User Guide

MAINTENANCE
PROCEDURES 10-7
Road wheel speed sensors
Inspect
Front wheel
Rear wheel
1.Inspect each sensor harness for damage.
Brake fluid
Replace
1.Replace brake fluid.

+ BRAKES, ADJUSTMENTS, Brake
system bleeding.
Fuel filter - diesel engine
Replace
1.Replace filter element.

+ ENGINE MANAGEMENT SYSTEM -
Td5, REPAIRS, Element - fuel filter.
Fuel filter sedimenter
Drain
1.Position suitable container beneath fuel filter.
2.Disconnect multiplug from sedimenter.
3.Rotate sedimenter anti-clockwise until water
flows from drain tube.
4.Allow to drain until diesel fuel flows from drain
tube.
5.Rotate sedimenter fully clockwise.
6.Connect multiplug.

ENGINE MANAGEMENT SYSTEM - V8
18-2-44 DESCRIPTION AND OPERATION
High tension (ht) leads
The ht leads are located on top of the engine, below the plenum chamber. Their function is to transfer the ht voltage
generated by the ignition coils to the spark plugs in the engine.
Input/Output
The input to the ht lead is ht voltage from the ignition coil pack. The ht lead then supplies this voltage to the spark
plug. Output ht voltage is used by the spark plugs to ignite the air/fuel mixture in the combustion chamber.
The ht leads can fail in the following ways:
lConnector/ Wiring fault.
lFaulty component causing spark tracking to chassis earth.
lDamage to ht leads during component removal.
In the event of a ht lead failure the following symptom may be observed:
lMisfire on specific cylinder.
All ignition system related faults are diagnosed by the misfire detection system and its fault codes.
Hill Decent Control (HDC)
Refer to Brakes for description of the hill descent control.

+ BRAKES, DESCRIPTION AND OPERATION, Description.
High/Low ratio switch
Refer to Transfer Box for description of the high/ low ratio switch transfer box components.

+ TRANSFER BOX - LT230SE, DESCRIPTION AND OPERATION, Description.

ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-71
Vacuum pump assembly
The vacuum pump assembly contains three components:
lThe vacuum pump.
lThe vacuum control valve.
lThe vacuum dump valve.
The vacuum pump provides the vacuum for the system while the two valves work in conjunction to allow the pump to
increase the vacuum to the pneumatic actuator (increase vehicle speed) or release vacuum from the pneumatic
actuator (decrease vehicle speed). On vehicles from 03 model year, the cruise control vacuum pump and pneumatic
actuator assembly is fitted with a heat shield to protect the components from heat from the exhaust manifold.
The vacuum control valve opens to allow the vacuum pump to increase the vacuum in the pneumatic actuator to
increase vehicle speed. When the vehicle reaches the set speed, the vacuum pump control valve closes to hold
vacuum in the pneumatic actuator and the vacuum pump is turned off by the cruise control ECU.
The vacuum dump valve is normally open. When cruise control is active, the cruise control ECU provides voltage to
close the vacuum dump valve. If power is lost, (e.g. when the brakes or clutch are applied or cruise control is turned
off at the cruise control master switch) the vacuum dump valve will immediately open and cruise control will be
deactivated.
The cruise control ECU provides power for all three components within the vacuum pump assembly. The cruise
control ECU provides earth control circuits for the vacuum pump and the vacuum control valve. The vacuum dump
valve is permanently grounded.
Input/Output
The cruise control ECU provides both power and earth to the components within the vacuum pump assembly. Current
draw at the vacuum pump assembly varies depending on components operating.
Vacuum pump current draw
When cruise is requested, the cruise control ECU provides voltage to the vacuum pump assembly and provides a
pulsed earth signal. The pulse period is dependent on the difference between the vehicle set speed and the actual
road speed. Removing the earth path switches off the pump.
Component State of components
Vacuum dump valve Off On On On
Vacuum control valve Off Off On On
Vacuum pump Off Off Off On
Current draw, amperes 0 0.23 0.37 2.14

REAR AXLE
REPAIRS 51-5
REPAIRS
Differential - assembly
$% 51.15.01
Remove
1.Raise rear of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Drain oil from differential.

+ MAINTENANCE, PROCEDURES,
Front and rear axle.
3.If same components are to be refitted,
reference mark propeller shaft and mating
components.
4.Remove 3 nuts and bolts securing flexible
coupling to pinion flange. Release propeller
shaft and tie aside.
5.Using tool LRT-51-008, extract the centralising
peg from the pinion flange. Remove the
centralising peg from the tool.6.Remove LH and RH rear brake discs.

+ BRAKES, REPAIRS, Brake disc -
rear.
7.Disconnect each ABS sensor multiplug.
8.Release each harness from brake hose and
hose bracket.
9.Remove 4 bolts securing each rear wheel hub
to rear axle.
M51 0041B
5
4
M51 0056
LRT-51-008

REAR AXLE
51-6 REPAIRS
10.Release and remove wheel hubs and drive
shafts from rear axle. Remove and discard 'O'
rings from wheel hubs.
11.Remove 10 bolts securing differential to axle.
Release and remove differential from axle. Refit
1.Clean drive shafts, wheel hubs and wheel hub
locations in rear axle.
2.Using a suitable solvent, remove all traces
sealant from differential and axle mating faces.
3.Apply sealant, Part No. STC 3811 to differential
or axle mating face.
4.Apply sealant, Part No. STC 50552 to threads
of differential securing bolts.
5.Fit differential to axle, fit bolts and tighten to 55
Nm (41 lbf.ft).
6.Clean pinion flange and centralising peg.
7.Using a tubular drift, fit centralising peg to
pinion flange. Ensure that the large diameter
part of the centralising peg is below pinion
flange mounting surface.
8.Position propeller shaft and align reference
marks.
9.Fit nuts and bolts securing flexible coupling to
pinion flange and tighten to 76 Nm (56 lbf.ft)
10.Lubricate 2 new wheel hub 'O' rings with clean
differential oil.

+ CAPACITIES, FLUIDS,
LUBRICANTS AND SEALANTS,
Lubrication. Install 'O' rings on wheel hubs.
11.Fit LH and RH drive shafts and wheel hubs to
rear axle. Fit wheel hub bolts and tighten to 100
Nm (74 lbf.ft).
12.Connect each ABS sensor multiplug and
secure harness to harness bracket and brake
hose.
13.Fit LH and RH rear brake discs.

+ BRAKES, REPAIRS, Brake disc -
rear.
14.Remove stand(s) and lower vehicle.
15.Fill differential with oil.

+ MAINTENANCE, PROCEDURES,
Front and rear axle.
M51 0042B

FRONT AXLE
REPAIRS 54-5
REPAIRS
Differential - assembly
$% 54.10.01
Remove
1.Raise front of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Remove front road wheels.
3.Drain oil from differential.

+ MAINTENANCE, PROCEDURES,
Front and rear axle.
4.If same components to be refitted, reference
mark propeller shaft and mating components.
5.Remove 4 nuts and bolts securing propeller
shaft to differential. Release propeller shaft and
tie aside.
6.Remove LH and RH front brake discs.

+ BRAKES, REPAIRS, Brake disc -
front.7.Disconnect each ABS sensor multiplug.
8.Release each harness from brake hose and
hose bracket.

FRONT AXLE
REPAIRS 54-7
13.Fit front brake discs.

+ BRAKES, REPAIRS, Brake disc -
front.
14.Fit front road wheels and tighten nuts to 140
Nm (103 lbf.ft).
15.Remove stand(s) and lower vehicle.
16.Fill differential with oil.

+ MAINTENANCE, PROCEDURES,
Front and rear axle.
Seal - differential pinion
$% 54.10.20
Remove
1.Raise front of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Reference mark front propeller shaft for
reassembly.
3.Remove 4 nuts and bolts securing propeller
shaft to differential. Release propeller shaft and
tie aside.
4.Using LRT-51-003 to restrain pinion flange,
remove bolt and washer securing pinion flange.
Remove pinion flange.
5.Position container to catch oil spillage.

FRONT AXLE
REPAIRS 54-9
Seal - oil - front axle casing
$% 54.15.04
Remove
1.Raise front of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Remove road wheel.
3.Remove front brake disc.

+ BRAKES, REPAIRS, Brake disc -
front.
4.Disconnect ABS sensor multiplug.5.Release harness from brake hose and hose
bracket.
6.Remove 4 bolts securing wheel hub to steering
knuckle.
7.Release wheel hub from steering knuckle.
8.Remove wheel hub and drive shaft from axle.

FRONT AXLE
54-10 REPAIRS
9.Remove oil seal from axle casing.Refit
1.Clean drive shaft oil seal recess, oil seal
running surface, wheel hub and swivel hub
mating faces.
2.Lubricate oil seal lip and running surface with
clean differential oil.

+ CAPACITIES, FLUIDS,
LUBRICANTS AND SEALANTS,
Lubrication.
3.Using tool LRT-54-012 and tool LRT-99-003,
fit new drive shaft oil seal to axle casing.
4.Apply anti-seize compound to wheel hub and
steering knuckle mating faces.
5.Ensure ABS harness is located in cut out in
steering knuckle.
6.Fit drive shaft and wheel hub to axle casing and
align wheel hub with steering knuckle. Fit wheel
hub bolts and tighten to 100 Nm (74 lbf.ft).
7.Connect ABS sensor multiplug and secure
harness to harness bracket and brake hose.
8.Fit front brake disc.

+ BRAKES, REPAIRS, Brake disc -
front.
9.Fit road wheel and tighten nuts to 140 Nm (103
lbf.ft).
10.Remove stand(s) and lower vehicle.
11.Check differential oil level.

+ MAINTENANCE, PROCEDURES,
Front and rear axle.

FRONT SUSPENSION
REPAIRS 60-33
Wheel hub
$% 60.25.01
Remove
1.Release ABS sensor harness grommet from
inner wing valance and disconnect multiplug.
2.Raise front of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
3.Remove road wheel.
4.Pull ABS sensor harness through aperture into
wheel arch.5.Release harness from brackets on inner wing
valance, suspension turret and front hub.
6.Release stake from drive shaft nut.
7.With assistance, remove drive shaft nut.
Discard the nut.
8.Remove front brake disc.

+ BRAKES, REPAIRS, Brake disc -
front.
9.Remove 4 bolts securing wheel hub to steering
knuckle.
10.Release wheel hub from steering knuckle, then
remove wheel hub and drive shaft assembly
from axle.
CAUTION: Do NOT remove the ABS sensor
from the hub. The hub and the sensor are
supplied as an assembly.