light LAND ROVER DISCOVERY 1995 Service Manual

ZF
21
REPAIR REPLACING PUMP
Service repair no - 44.32.01
1.Remove gearbox and transfer box assembly.
See LT230T Transfer Gearbox
2.Place gearbox on bench. Remove torque
converter using torque converter handles
18G1501, taking care not to damage torque
converter/oil pump housing oil seal.
3.Remove twelve bolts (inner ring pattern).
4.Remove bell housing and pump assembly from
gearbox case, discard gasket.
5.Remove eight bolts on rear of pump.
6.Screw in two bolts,diagonally opposite each
other, tap lightly using a soft headed mallet to
free pump assembly from intermediate plate.
7.Fit new pump assembly, aligning dowel with hole
in intermediate plate, press pump housing home.
8.Secure pump housing to intermediate plate
using eight hexagonal bolts. Tighten to
10 Nm.
9.Place bell housing and intermediate plate
assembly on bench, front face up. Using oil
pump rotation sleeve LST111, check that pump
gears rotate freely.
10.Before replacing intermediate plate/bell housing
assembly check that thrust washer and axial
cage are seated on A clutch housing.
11.Place new gasket and disc washer onto bell
housing and intermediate plate assembly using
a Petroleum Jelly.
12.Fit bell housing and intermediate plate assembly,
tighten twelve bolts to
46 Nm.

51REAR AXLE AND FINAL DRIVE
4
REPAIR Refit
10.Clean stub axle. Retract ABS sensor slightly
from sensor sleeve, if applicable
11.Fit hub assembly to stub axle.
12.Fit spacing washer.
13.Fit hub adjusting nut. Tighten to
61 Nm.
Back off adjusting nut 90°. Tighten to4 Nm.
This will give the required hub end float of
0,010mm
14.Fit a new lock washer.
15.Fit locknut. Tighten to61 Nm.
16.Tab over lock washer to secure adjusting nut
and locknut.
17.Using a new joint washer fit axle shaft to hub,
secure with five bolts. Tighten to
65 Nm.
18.Fit brake caliper. Tighten to82 Nm.
Secure brake pipes to axle casing.
19.If applicable, set ABS brakes sensor.
Push sensor in until it touches sensor ring then
rotate hub to set sensor.
20.Fit road wheel, remove axle stands and final
tighten road wheel nuts to
126 Nm.
21.Operate footbrake to locate brake pads before
driving vehicle.

STEERING
3
FAULT DIAGNOSIS STEERING DAMPER
The power steering system, as well as reducing the
effort required to manoeuvre the vehicle when
parking, also helps to dampen any deflections of the
road wheels, being transmitted back to the steering
wheel.
When operating the vehicle off road, the road wheels
are often deflected by ruts and boulders causing the
steering wheel to turn left and right. This phenomenon
is known as 'steering kickback'. To subdue the effects
of 'steering kickback', a hydraulic damper is fitted in
the steering linkage between the track rod and the
differential casing. The damper, which offers the same
resistance in extension and compression, is sealed for
life.
Steering damper check
Check the condition operation of the hydraulic
steering damper as follows:
Check procedure
1.Inspect damper for casing damage or leaks.
2.Clamp one end of the damper horizontally in a
vice using soft jaws. Compress and extend the
unit by hand. Resistance should be equal in both
directions.
3.If it is felt that the unit is outside acceptable
limits, fit a new steering damperSTEERING FAULTS
Symptom:-
Excessive kickback through steering wheel - when
driven on rough terrain.
1.Is the steering damper in good working order?
See Steering Damper
NO - Renew unit.See Repair, Steering
Damper
YES - Continue.
2.Is there any looseness or free play in the
steering ball joints and linkage?
YES -
See Steering Linkage Inspect
NO - Continue.
3.Is there any looseness or worn bushes in front
suspension?
YES -
See FRONT SUSPENSION, Repair,
Radius Arm
NOTE: When replacing suspension bushes
ALL bushes and fixings must be replaced.
NO - Continue.
4.Is the steering exceptionally light/sensitive when
driven on good road surface?
YES - See fault symptom -Steering
excessively light/sensitive and
freeplay at steering wheel.
NO - Suspect axle swivel resistance.
5.Check the resistance of the axle swivels.
See
FRONT AXLE AND FINAL DRIVE, Overhaul,
Front Stub Axle, Constant Velocity Joint and
Swivel Pin Housing Non ABS See FRONT
AXLE AND FINAL DRIVE, Overhaul, Front
Stub Axle, Constant Velocity Joint and
Swivel Pin Housing ABS

STEERING
5
FAULT DIAGNOSIS Symptom :-
Steering excessively light/sensitive. Excessive
freeplay at steering wheel.
1.Are steering box adjustments correct?
NO -
See Adjustment, Power Steering Box
WARNING: Adjustments of steering box
should not be required while in warranty
period. If box is within warranty, it must be
returned to manufacturer. No attempt must be
made to introduce backlash.
YES - Suspect worn panhard rod or radius arm
bushes Check condition of ball joints and
the lower steering column shaft universal
joints for wear.
See Repair, Lower
Steering Shaft and Universal Joints
Symptom :-
Steering vibration, road wheel shimmy - wobble.
Vibration through the steering linkage powerful
enough to induce high frequency oscillation of the
steering wheel, is generally caused by out of balance
road wheels. However there are a number of other
possible causes of this symptom which if severe, may
be described as shimmy or wobble. Regardless of the
terminology used by the owner/driver to describe the
symptoms, the following diagnostic checks should be
carried out in the order presented.
1.Check the tyres and balance of the road wheels.
See GENERAL SPECIFICATION DATA,
Information, Wheels and Tyres See
WHEELS AND TYRES, Fault diagnosis, Fault
- Symptoms See WHEELS AND TYRES,
Repair, Wheel Balancing
2.Check the steering hydraulic damper function.
See Steering Damper
3.Check steering column universal joints for wear
and correct alignment.
See Repair, Lower
Steering Shaft and Universal Joints
4.Check steering linkage ball joints for wear,
correct alignment and security, including steering
box and tie rod.
See Steering Linkage Inspect
5.Check all front suspension rubbers for wear.
Check all fixing torques, including radius arm
bushes, panhard rod and anti-roll [sway] bar.
See FRONT SUSPENSION, Repair, Panhard
Rod See FRONT SUSPENSION, Repair,
Radius Arm See FRONT SUSPENSION,
Repair, Anti-Roll[Sway] Bar Assembly See
FRONT SUSPENSION, Repair, Front Shock
Absorber
6.Fit new radius arm bushes using NTC 6860. Fit
harmonic damper if vehicle has air suspension.
Fit new nuts, bolts and washers.
7. Coil spring vehicles only- If problem persists
fit damper kit STC 241 (2 off front) and STC
1474 (2 off rear). Road test vehicle.
8.Check the power steering box adjustments and
operation.
See Overhaul, Power Steering Box
9.Check the hub bearing end floats and determine
the condition of the hub bearings. As applicable.
See FRONT AXLE AND FINAL DRIVE, Repair,
Front Hub Assembly
10.Check the resistance and condition of the
swivels.
See FRONT AXLE AND FINAL
DRIVE, Description and operation,
Description
If problem is not diagnosed: Repeat
checks starting at 1.
11.Carry out a full steering geometry check.
See
INTRODUCTION, Information, Steering

BRAKES
1
DESCRIPTION AND OPERATION BRAKES
Discovery vehicles have servo assisted brake
systems and the option of an anti-lock brake system.
Information in this section refers to components
relevant to both brake systems. Where the system
components are different they are referred to as ABS
or NON ABS
BRAKE SYSTEM NON ABS
Description
The servo assisted hydraulic braking system is the
dual line type, incorporating primary and secondary
hydraulic circuits.
NOTE: References made to primary or
secondary do not imply main service
brakes or emergency brakes but denote
hydraulic line identification.
The brake pedal is connected to a vacuum assisted
mechanical servo which in turn operates a tandem
master cylinder. The front disc brake calipers each
house four pistons, these pistons are fed by the
secondary hydraulic circuit. The rear disc brake
calipers each house two pistons, these are fed by the
primary hydraulic circuit via a pressure reducing valve.
A brake fluid level switch is incorporated into the
reservoir cap assembly, the switch will immediately
illuminate a warning light in the instrument binnacle
indicating low fluid or sudden fluid loss.
The brake fluid reservoir is divided, the section closest
to the servo feeds the primary circuit and the section
furthest from the servo feeds the secondary circuit.
Under normal operating conditions both the primary
and secondary circuits operate simultaneously on
brake pedal application. In the event of a failure in the
primary circuit the secondary circuit will still function. If
the secondary circuit fails the primary circuit will still
function. The brake pedal travel will be longer in the
event of a half system failure.If the servo should fail, both hydraulic circuits will still
function but would require greater pedal effort due to
the lack of vacuum assistance. The hand operated
parking brake acts on a brake drum at the rear of the
transfer gearbox and is completely independent of the
hydraulic circuits.
Hydraulic circuit non ABS
Key
A = Primary hydraulic circuit
B = Secondary hydraulic circuit
C = Pressure reducing valve

70BRAKES
4
DESCRIPTION AND OPERATION System description
The brake system consists of dual hydraulic circuits in
a front - rear split. That is individual circuits to front
and rear axles.
Wheelspeed signals are provided by the fitting of
exciter rings to axles and speed sensors.
An ABS stop light switch is fitted to provide a braking
signal to the ECU as well as operate the stop lights.
Electrical wiring is provided as necessary with system
relays and fuses. Discovery Electrical Troubleshooting
Manual gives the location and wiring circuits of these
components.
Visual warning of system malfunction is provided via a
warning light in the instrument panel.
Hydraulic circuit ABS
Key
A = Primary hydraulic circuit
B = Secondary hydraulic circuit
C = Pressure reducing valve
D = ABS ModulatorABS System operation
During normal braking the feel of the brake pedal on
vehicles equipped with ABS will be the same as that
on non ABS vehicles. During ABS cycling the driver
will experience feedback in the form of a pulsating
brake pedal and solenoid/pump motor noise from the
Modulator.
The system is fully automatic in operation both on and
off road, and will only act when the ECU detects that
ABS cycling is necessary. The ECU continually
monitors the operation of the system.
When starting the ABS system will go through a series
of self checks, including a check of the solenoid
valves/pump motor.
WARNING LIGHT
The warning light will be on during the self check
(1.3-2 secs). If no faults are stored in the memory the
light goes out for 0.5sec,then comes on again. It will
then remain on until the vehicle is driven faster than 7
kph/5mph. This is the only time that the light will be on
without indicating a problem.
Any faults detected by the ECU will cause the warning
light to illuminate indicating that the vehicle may not
have full ABS control.

70BRAKES
8
DESCRIPTION AND OPERATION Brakes applied
When the brake pedal is depressed the pedal pushrod
operates valve C situated in the plastic diaphragm hub
9 and 10. Inital depression of the the brake pedal,
push rod 6 and plunger 7 compress a rubber pad 8.
This slight movement causes valve C to close port D
sealing off the vacuum to chambers 2/4 and allows
atmospheric pressure to enter the chambers through
the air filter E.
With depression in chambers 1/3 and air pressure in
chambers 2/4 the servo hub will apply the brakes via
the master cylinder push rod 13.Atmospheric pressure over the large area of the
diaphragms multiples the force applied to the master
cylinder piston, to provide the power assistance. If the
brake pedal is only partially depressed, the servo hub,
diaphragms and master cylinder push rod will stop
moving, when valve C comes to rest on the plunger 7.
At this point the valve will balance the pressure in all
the chambers, to the applied effort at the pedal and
provide proportional braking.
It is only when the brakes are fully applied that the
valve does not balance the pressures in all the
chambers, but ensures that maximum available
depression is in chambers 1/3 and full atmospheric
pressure enters chambers 2/4.
When the brake pedal is released, the pressure in all
chambers is equalised and the servo is returned to the
rest position by spring 12.

BRAKES
1
FAULT DIAGNOSIS ABS FAULT DIAGNOSIS
If a fault has occurred, or has been identified by ECU
self diagnostic function and ABS warning light is
illuminated. The system and components must be
checked to locate and rectify fault, using Testbook
diagnostics.
NOTE: If warning lamp has indicated a
fault in system, and no fault code has been
stored in memory, cause of fault is:
a) Failure in electrical supply
b) Bad ECU ground
c) Faulty warning light relay
d) ECU not connected
Before commencing fault diagnosis procedure
following items must be checked:
1.Inspect all exposed cables for damage or
abrasion.
2.Check ground on ABS system.
3.Battery - state of charge.
4.Check hub end-float.
5.All ABS fuses and electrical connections.
Fault rectification
1.Complete harness should be replaced if faults
are found in wiring harness.
2.DO NOT use unspecified cables or connectors,
as this could jeopardise safe function of ABS.
3.DO NOT attempt to open sealed 35 way
connector to ECU.FAULT DIAGNOSIS PROCEDURE
NOTE: If ABS warning light illuminates due
to large sensor air gap, fault will be
retained by the ECU memory. Where wheel
sensors have been pushed fully home prior to
test, The ECU will indicate a fault that has been
rectified.
NOTE: After any steering adjustment,
bearing replacement/adjustment, brake
disc replacement: Check hub end-float and
sensor clearance.
RELAYS AND FUSES ABS
The location and identification of ABS electrical relays
are given in the Electrical Troubleshooting Manual
For location and identification of ABS electrical fuses.
See ELECTRICAL, Repair, Fuse Box - Interioror.
See ELECTRICAL, Repair, Fuse Box - Engine
Compartment

70BRAKES
2
FAULT DIAGNOSIS ABS FAULT AND REMEDY CHART
SYMPTOM POSSIBLE CAUSE CHECK REMEDY
ABS warning light on ABS electrical fault Check ABS electrical
circuit with Testbook
diagnostic equipmentChange component if
necessary
High sensor air gaps Push in sensors
Brake fluid warning light
ONFluid loss Check reservoir fluid level
and inspect system for
leaksRectify leakage, refill
reservoir
Reservoir fluid level
switch malfunctionCheck fluid level switch Change reservoir
cap/switch
Pedal travel increased,
foot pressure normalAir in system Rebleed brake system
Master cylinder
malfunctionChange master cylinder
Pedal can be moved
downwards under
constant pressureSeal leaking in master
cylinderInspect system for leaks Change master cylinder
Seal leaking in servo unit Change servo unit

BRAKES
7
REPAIR 19.Coat new seals in unused brake fluid. Fit 'L' seal
to plunger.
20.Fit washer followed by recuperating seal. Fit seal
retainer and springs, ensure springs are
correctly seated.
Assembling master cylinder
CAUTION: It is important that following
instructions are carried out precisely,
otherwise damage could be caused to new
seals when inserting plungers into cylinder bore.
Generous amounts of new brake fluid should be
used to lubricate parts during assembly.
21.Fit new swirl tube to bottom of cylinder bore.
22.Lubricate secondary plunger and cylinder bore.
Offer plunger assembly to cylinder until
recuperation seal is resting centrally in mouth of
bore. Gently introduce plunger with a circular
rocking motion, as illustrated. Ensuring that seal
does not become trapped, ease seal into bore
and slowly push plunger down bore in one
continuous movement.
23.Fit new primary plunger assembly using same
method as for secondary plunger.
24.Fit original guide ring to support primary plunger.
25.Coat a new 'O' ring with brake fluid and fit to its
respective groove on outer location surface of
master cylinder.
CAUTION: Do not roll 'O' ring down outer
location surface of master cylinder. It
should be slightly stretched and eased
down cylinder and into its groove. Do not over
stretch seal.
26.Fit new retaining ring on outer surface of master
cylinder ensuring that serrations of ring are
facing mounting flange.
27.Fit two new reservoir seals in respective ports.
28.Fit a new vacuum seal to either primary plunger
or to bottom of transfer housing bore, open face
of seal towards primary plunger.
29.Lubricate vacuum seal with brake fluid. Fit
transfer housing to master cylinder, push
housing fully up to cylinder mounting flange, Do
not adjust transfer housing after fitting.
30.Lubricate new water ingress seal with brake
fluid, Slightly stretch seal and ease down
housing until it is in position between housing
and flange.
31.Roll reservoir into top of master cylinder,
reversing procedure described in instruction 10.
Refit
NOTE: Ensure O ring seal between master
cylinder and servo unit is fitted correctly.
32.Fit master cylinder to servo. Secure in position
with two nuts, plain and spring washers. Tighten
to
26 Nm.
33.Fit brake pipes to master cylinder. Tighten to
15Nm.
34.Top-up master cylinder with correct grade of
brake fluid.
See LUBRICANTS, FLUIDS AND
CAPACITIES, Information, Recommended
Lubricants and Fluids
35.Bleed system.See Brake System Bleed
36.Fit cap, reconnect electrical lead to fluid level
switch. Reconnect battery negative lead.