1995 LAND ROVER DISCOVERY engine

BRAKES
9
DESCRIPTION AND OPERATION Petrol engine vacuum system
The vacuum necessary to operate the brake servo on
petrol engine vehicles is provided by the engine inlet
manifold. During normal operation of the brakes only a
small volume of air is drawn from the servo and into
the inlet manifold or plenum chamber. However any
excessive air leaks due to damage in the brake servo
system or manifold hose connection, will effect the
mixture strength and ECM fuelling calculations on
engines equipped with an MFI system.
Diesel engine vacuum system
As the diesel engine inlet system does not produce
depression sufficient to operate the brake servo, it is
necessary to install an engine driven vacuum pump.
During normal operation of the brakes only a small
volume of air is drawn from the servo by the vacuum
pump. However as the pump exhausts air into the
engine crankcase atmosphere, an air leak due to
damage in the brake servo system or pump hose
connection, may cause excessive crankcase
pressure.

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

BRAKES
1
REPAIR GENERAL BRAKE SERVICE PRACTICE
Brake fluid precautions
WARNING: Do not allow brake fluid to
come into contact with eyes or skin.
CAUTION: Brake fluid can damage
paintwork, if spilled wash off immediately
with plenty of clean water.
CAUTION: Use only correct grade of brake
fluid. If an assembly fluid is required use
ONLY brake fluid. Do NOT use mineral oil,
i.e. engine oil etc.
CAUTION: Thoroughly clean all brake
calipers, pipes and fittings before
commencing work on any part of the brake
system. Failure to do so could cause foreign
matter to enter the system and cause damage to
seals and pistons which will seriously impair the
efficiency of the brake system.
·To ensure the brake system efficiency is not
impaired the following warnings must be
adhered to :-
·DO NOT use any petroleum based cleaning
fluids or any proprietary fluids containing
petrol.
·DO NOT use brake fluid previously bled from
the system.
·DO NOT flush the brake system with any fluid
other than the recommended brake fluid.
The brake system should be drained and flushed
at the recommended service intervals.
Cover all electrical terminals carefully to make
absolutely certain that no fluid enters the
terminals and plugs.FLUID LEVEL CHECK / TOP UP
WARNING: Clean reservoir body and filler
cap before removing cap. Use only fluid
from a sealed container.
1.Park vehicle on level ground.
2.Check level is between 'MIN' and 'MAX' marks.
3.If level is below 'MIN' mark top up fluid level to
'MAX' mark on reservoir, using correct fluid.
See
LUBRICANTS, FLUIDS AND CAPACITIES,
Information, Recommended Lubricants and
Fluids
Do not fill reservoir above maximum line

75SUPPLEMENTARY RESTRAINT SYSTEM
2
DESCRIPTION AND OPERATION OPERATION
The airbag supplementary restraint system (SRS) is a
safety device which, when used in conjunction with
the seat belt, is designed to protect the driver and
front passenger.
Two different SRS systems are fitted to Discovery.
The Distributed SRS which has two crash sensors
located in the engine compartment on the chassis
longitudinals and the Single Point Sensing (SPS) SRS
which has a single crash sensor located in the Airbag
diagnostic control unit.
The change from distributed SRS to SPS SRS
occurred at VINs198222and528977.
Distributed SRS
In the event of a frontal impact, when the airbag
diagnostic control unit and one of the airbag crash
sensors senses the impact, the diagnostic control unit
fires igniters. This in turn ignites tablets of sodium
azide which generate a large amount of Nitrogen gas
leading to airbag inflation in approximately 30
milli-seconds.SPS SRS
In the event of a frontal impact, when the airbag
diagnostic control unit senses the impact, the
diagnostic control unit fires igniters. This in turn ignites
tablets of sodium azide which generate a large
amount of Nitrogen gas leading to airbag inflation in
approximately 30 milli-seconds.
All Models
When fully deployed the airbag offers additional
protection to the front seat occupant. As an occupant
moves into the airbag it immediately discharges the
gas to provide progressive occupant deceleration and
reduce risk of injuries. The whole process is
completed in approximately 0.3 seconds.
WARNING: All the airbag system
components, including the wiring harness,
MUST be renewed after the airbags have
deployed.

HEATING AND VENTILATION
3
DESCRIPTION AND OPERATION
Controls set for unheated air to footwells and face level vents
Heater and ventilation operation
The heating and ventilation system contains a heater
matrix, which is connected to the engine cooling
system, and a 4 speed fan for air distribution. Engine
coolant is circulated through the heater matrix
continuously, except when the temperature controls
are set to COLD.
Recirculated air
When the recirculation switch is pressed, an electrical
servo operates and fully closes the fresh air intake
flap.
Fresh air
When the recirculation switch is returned to the OFF
position, the electrical servo returns and fully opens
the fresh air intake flap.Heated air
Temperature output is controlled by the temperature
controls which move the air direction and temperature
flaps independently to increase or decrease the
volume of air flow through the heater matrix.
V8 Engine:When both controls are in the cold
position, the coolant valve is turned off.
Face level vent flap
Control at face level, flap fully open. All other vents
closed.
Control at face and foot level, flaps half open.
Unless an air conditioning unit is fitted, only fresh or
re-circulated air is available from the face level vents.
Demist vent flap
Control at demist, flap fully open. All other vents
closed.
Control at demist and foot level, flaps half open.

80HEATING AND VENTILATION
4
DESCRIPTION AND OPERATION Air direction flap
Flap moves across mixing chamber to direct the air
flow away from the heater matrix.
Air temperature flap
Control at HOT, flaps fully closed. All air flow passes
through heater matrix. As control is moved towards
COLD the flaps progressively open directing air flow
away from the heater matrix.
Control at COLD, flaps fully open.
V8 Engine:When both controls are at COLD, 2
micro-switches are closed and operate a vacuum
valve which closes the coolant valve.Air conditioning
When an air conditioning unit is fitted, the mechanical
operation of the heater controls remains unaltered.
However the air conditioning evaporator is positioned
in front of the mixing chamber through which all air
flow passes.

HEATING AND VENTILATION
1
FAULT DIAGNOSIS HEATER OUTPUT
Symptom:-
Heater emits cold air.
1.Engine running: Check coolant valve opens as a
temperature control is moved from COLD.
2.Check for engine running cold.
See COOLING
SYSTEM, Fault diagnosis, Engine Runs Cold
3.Check heater pipes and hoses for blockage or
restriction.
4.Check heater matrix for blockage or restriction,
flush system.
Heater emits warm air.
5. Engine running:Check coolant valve closes
when both temperature controls are moved to
COLD.

80HEATING AND VENTILATION
4
REPAIR WATER VALVE
Service repair no - 80.10.16
Remove
1.Disconnect vacuum pipe from water valve.
2.Slacken 4 clips securing hoses to water valve.
3.Use a thin blade to break seal between hoses
and nozzles
4.Disconnect heater inlet hose from valve.
NOTE: A quantity of coolant will be
released.
5.Disconnect heater outlet hose from valve.
6.Lever valve from coolant pipe hoses.
Refit
7.Reverse removal procedure. Lightly lubricate
water valve nozzles with petroleum jelly.
8.Reverse removal procedure. Top-up engine
coolantVACUUM SWITCH - WATER VALVE
Service repair no - 80.10.36
Remove
1.Release emission pipe from retaining clip.
2.Remove bolt securing switch to bulkhead.
3.Disconnect multiplug from switch.
4.Disconnect 2 vacuum pipes and remove vacuum
switch.
Refit
5.Reverse removal procedure.