relay LAND ROVER DISCOVERY 1995 Owner's Guide

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
22
REPAIR MODULATOR UNIT
Service repair no - 70.65.45
WARNING: New modulator units are
supplied in a shock absorbing pack
marked with a use by date. The new
modulator will contain hydraulic brake fluid within
the valve block and all ports plugged.
Modulator units must be handled with care the
following must be avoided:- any impact, use of
compressed air on any of the hydraulic ports,
removing plugs to connection ports before fitting
unit.
Remove
1.Refer to the illustration of brake components
ABS. For details of modulator unit and hydraulic
pipe connections to it.
See Brake
Components ABS
2.Refer to general brake service practice.See
General Brake Service Practice
3.Check new modulator unit is packaged in
accordance with the WARNING above.
4.Disconnect battery negative lead.
5.Remove the two electrical plugs.
6.Identify 8 pipe to modulator connections for
correct reassembly.
7.Disconnect 8 pipe unions.
8.Remove nuts securing modulator to mounting
bracket.
9.Remove modulator unit.
10.Remove mounting bushes and cup.
Refit
11.Fit mounting bushes and cup to new modulator.
12.Fit modulator unit to mounting bracket.
13.Fit 8 pipes to modulator connections. Pipes
mustbe connected to correct port. Tighten to
15Nm.
14.Bleed the complete hydraulic system.See
Brake System Bleed
15.Check system function using the 'Testbook'
diagnostics
16.Test operation of brakes.ELECTRONIC CONTROL UNIT ABS
Service repair no - 70.65.01
Remove
For location of the ECU.
See Description and
operation, ABS Components
1.Disconnect battery negative lead.
2.Remove retaining bolt and lower alarm system
ECU and relay mounting bracket into passenger
footwell.
3.Remove two screws and detach ECU complete
with harness plug from mounting bracket.
4.Release ECU plug retaining clip.
5.Move plug in direction of arrow and release
hooked end of plug from retaining post.
Refit
6.Reconnect ECU harness plug ensuring that it is
firmly located and retaining clip secures plug.
7.Reverse removal procedure.

CHASSIS AND BODY
47
REPAIR
14.Remove 2 screws securing louvre panel.
15.Remove louvre panel from dash panel.
Refit
16.Position louvre panel, feed harness connectors
through their correct apertures,and align to dash
panel.
CAUTION: When refitting avoid trapping of
electrical wiring.
17.Fit and tighten screws securing louvre panel.
18.Fit panel retaining screw cover.
19.Position heater control unit to panel and secure
with screws.
20.Fit heater graphic display panel and secure with
screws.
21.Fit heater control and blower switch knobs.
22.Fit clock.
See ELECTRICAL, Repair, clock.
23.Position coin tray and secure to tags.
24.Position radio cage, feed electrical connectors
and aerial through cage, and position to panel.
25.Bend back radio cage retaining tags.
26.Fit radio.
See ELECTRICAL, Repair, radio.
27.Connect battery negative lead.DASH PANEL ASSEMBLY
Service repair no - 76.46.23
Remove
1.Move front seats to rearmost position.
2.Disconnect battery negative lead.
3.Disconnect air bag multiplugs under dash panel.
CAUTION: When air bags are fitted,
reference must be made to the Airbag
Supplementary Restraint System section.
4.Remove passenger glove box.
5.Remove driver's side access panel.
6.Remove centre console assembly.
See centre
console.
7.Remove airbag from steering wheel.See
SUPPLEMENTARY RESTRAINT SYSTEM,
Repair, driver's airbag module.
8.Remove passenger's airbag from dash panel.
See SUPPLEMENTARY RESTRAINT SYSTEM,
Repair, passenger's airbag module.
9.Release clamp and lower steering column.
10.Remove steering wheel.
See STEERING,
Repair, steering wheel.
11.Remove column switch.See
SUPPLEMENTARY RESTRAINT SYSTEM,
Repair, column switch assembly.
12.Remove instrument binnacle.See
ELECTRICAL, Repair, instrument binnacle.
13.Remove radio.See ELECTRICAL, Repair,
radio.
14.Remove exterior mirrors switch panel.
15.Remove coin tray.
16.Remove switch panel.
17.Remove clock.
18.Undo screw securing mounting bracket and
position passenger's side relay assembly aside.
19.Set heater controls fully clockwise.

CHASSIS AND BODY
49
REPAIR Refit
CAUTION: When refitting avoid trapping
electrical wiring.
29.Reverse removal procedure.
30.With assistance: Position dash panel and
connect dash harness multiplugs to fusebox and
main harness.
31.Reverse removal procedure. Ensure dash panel
upper bracket studs are located before the 4
lower brackets.
32.Reverse removal procedure. Disconnect
glovebox switch Lucars to ease fitting of relay
bracket.WINDSCREEN GLASS
Service repair no - 76.81.01
Information
The following equipment is required:
·Cutting wire and handles
·Windscreen repair kit (see Technical
Bulletin).
See Electrical Trouble Shooting
Manual.Windscreen Glass Replacement.
·Sealant applicator gun.
·Suction cup lifters.
The following materials are included in the windscreen
repair kit:
·Glass cleaning solvent - 'Betawipe' Glass
activator (yellow cap).
·Cotton buds.
·Glass primer - 'Betaprime'(green cap).
·Body primer - 'Betaprime' paint/plastic
primer (red cap).
·Betaseal Adhesive sealant.
NOTE: The adhesive sealant cures in 6 to 8
hours
CAUTION: Once existing sealant is cut, the
exposed surfaces oxidises in
approximately 90 minutes. The refit
procedure must be completed within this time
span to prevent the sealant oxidising, to effect a
satisfactory joint.
CAUTION: If the windscreen aperture body
flange shows signs of corrosion it must be
treated with anti corrosion primer and
repainted. Newly painted areas must then be left
for 8 hours or more before applying adhesive
sealant.

HEATING AND VENTILATION
1
DESCRIPTION AND OPERATION HEATING AND VENTILATION UNIT
The heating and ventilation and blower units are
standard on all models. Air conditioning system is an
optional module, which when fitted provides fully
integrated climate control for the vehicle interior.
The heating and ventilation unit controls the air
distribution and heating to the vehicle interior. The
blower unit controls the volume of air supplied, while
the air conditioning module (when fitted) provides
refrigerated and dehumidified air.
1. Fresh air inlet
2. Recirculation air inlet
3. Air outlets screen de-mist
4. Air outlet face level vents
5. Air outlets front footwells
6. Air outlets to rear footwells7. Fresh/recirculation air flap servo
8. Blower motor relay
9. Multiplug connector to main harness
10. Multiplug connector, blower to heater unit
11. Resistor unit - blower speed.

AIR CONDITIONING
3
DESCRIPTION AND OPERATION AIR CONDITIONING SYSTEM OPERATION
The air conditioning system provides the means of
supplying cooled and dehumidified, fresh or
recirculated air to the interior of the vehicle. The
cooling effect is obtained by blowing air through the
matrix of an evaporator unit and when required,
mixing that air with heated air by means of the heater
distribution and blend unit, to provide the conditions
required inside the vehicle. The volume of conditioned
air being supplied is controlled by a variable speed
blower.
A sealed system, charged with Refrigerant R134a,
together with a blower unit, blend unit and control
system combine to achieve the cooled air condition.
For air conditioning air distribution system.
See
HEATING AND VENTILATION, Description and
operation, Heating and ventilation unit
The air conditioning system comprises five major
units:
1.An engine-mounted compressor.
2.A condenser mounted in front of the radiator.
3.A receiver/drier unit located in front of the
condenser.
4.Thermostatic expansion valve mounted above
the evaporator.
5.An evaporator unit mounted in front of the heater
matrix.
NOTE: Vehicles fitted with rear air
conditioning have an additional
evaporator/blower motor assembly located
behind the LH rear compartment lower trim panel.
These units are interconnected by hoses and pipes
carrying Refrigerant R134a, the evaporator is linked
into the vehicle ventilation system.
Refrigeration cycle
1. Compressor
The compressor (1), belt driven from the crankshaft
pulley, pressurises and circulates the refrigerant
through the system. Mounted on the compressor, an
electro-mechanical clutch maintains the correct
temperature and pressure by engaging or disengaging
to support the system's requirements. The clutch
action is normally controlled by a thermostat located
at the evaporator (5). The compressor is of the
swashplate type having fixed displacement.Should the temperature at the evaporator (5) fall low
enough for ice to begin to form on the fins, the
thermostat disengages the clutch and also isolates the
cooling fans relays. When the temperature at the
evaporator (5) rises to the control temperature, the
clutch is re-engaged.
Should the system pressure become excessive or
drop sufficiently to cause damage to the compressor
(1) a dual pressure switch (7), located in the high
pressure line, signals the relay unit to disengage the
clutch. The compressor also has an emergency high
pressure relief valve (9) fitted.
The cooling fans are controlled by engine temperature
when the air conditioning is not switched on.
2. Condenser
From the compressor, hot high pressure vaporised
refrigerant (F1) passes to the condenser (2), which is
mounted in front of the engine coolant radiator. Ram
air(A1) passing through the condenser (2),
supplemented by 2 cooling fans (8) mounted in front
of the condenser, cools the refrigerant vapour
sufficiently to form a high pressure slightly subcooled
liquid (F2).
3. Receiver/drier
This liquid then passes to a receiver/drier (3) which
fulfils two functions. It acts as a reservoir and moisture
extractor (11).
A sight glass (10), in the high pressure line, provides a
method of determining the state of the refrigerant
without breaking into the system.
4. Expansion valve
From the receiver/drier (3) the moisture free high
pressure liquid refrigerant (F3) passes through a
thermostatic expansion valve (4). A severe pressure
drop occurs across the valve and as the refrigerant
enters the evaporator space at a temperature of
approximately -5°C it boils and vaporises.

82AIR CONDITIONING
4
DESCRIPTION AND OPERATION 5. Evaporator
As this change of state occurs, a large amount of
latent heat is absorbed. The evaporator is therefore
cooled and as a result heat is extracted from the air
flowing across the evaporator. The air flow is
controlled by the ventilation fan which can be
operated at anyone of four speeds.
To prevent liquid passing through to the compressor,
a capillary tube (6), attached to the outlet pipe of the
evaporator (5) and connected to the thermostatic
expansion valve (4), controls the amount that the
valve opens and closes in relation to the temperature
of the low pressure high temperature refrigerant
vapour (F4) at the outlet. The atomised refrigerant
then passes through the evaporator (5). Fan blown air
(A2) passes through the matrix (A3) of the evaporator
and is cooled by absorption due to the low
temperature refrigerant passing through the
evaporator.
A thermostat is fitted in the airflow out of the
evaporator to sense the temperature of the exterior
fins. Should ice begin to form, due to a too cold
condition, it will signal to disengage the
electro-mechanical clutch on the compressor (1).
From the evaporator, low pressure slightly
superheated refrigerant (F5) passes to the
compressor to complete the cycle.AIR CONDITIONING CONTROL SYSTEM
The air conditioning control system comprises relays,
thermostat, pressure switches, and a control panel.
Inputs from outside the air conditioning system
comprise temperature information from the engine
cooling system. Together these controls, in
conjunction with the cooling fans, compressor clutch,
blower and heater distribution and blend unit enable
minimal input to maintain the required environment
inside the vehicle.
When air conditioning is not selected, air is supplied
by ram effect or blower to the areas selected by the
controls. The air mix flap on the blend unit controls the
temperature of the air being supplied. No cooled air is
available.
Selecting air conditioning provides the added facility of
cooled air available to be mixed as before. When
required a fully cold condition can be selected by
turning the temperature controls to cold, which
automatically closes the heated coolant access to the
heater matrix. Mixtures of cooled, fresh, and hot air
can be selected to give required interior environmental
conditions by selection at the control panel.
Dual pressure switch
This switch, located in the high pressure line between
the receiver drier and the expansion valve, monitors
refrigerant pressure and by means of the relay module
controls the following system functions:
1.Refrigerant pressure drops below 2.0 bar, 29
lbf/in
2(due to possible leakage), the
compressor's electro-mechanical clutch is
dis-engaged.
When pressure rises above 2.0 bar, 29 lbf/in
2the
compressor's clutch is re-engaged.
2.Refrigerant pressure rises above 32 bar, 455
lbf/in
2(due to possible blockage), even with
cooling fan operation, the compressor's
electro-mechanical clutch is dis-engaged.
When the pressure drops below 26 bar, 375
lbf/in
2the compressor clutch is re-engaged.

AIR CONDITIONING
1
FAULT DIAGNOSIS AIR CONDITIONING FAULTS
FAULT CAUSE REMEDY
1. Incorrect voltage. 1. Check voltage.
A.2. Open or defective fuse or relay. 2. Check and replace as necessary.
BLOWER3. Loose wire connection including 3. Check system wires; tighten
MOTORground. all connections.
INOPERATIVE4. Switch open or defective. 4. Replace switch.
OR SLOW5. Tight, worn, or burnt motor 5. Replace motor.
RUNNINGbearings.
6. Open rotor windings. 6. Replace motor.
7. Worn motor brushes. 7. Replace motor.
8. Shaft binding-blade misaligned. 8. Check alignment. Repair or replace
as necessary.
9. Defective resistors 9. Rectify or replace.
1. Incorrect voltage. 1. Check voltage.
2. Open or defective fuse or relay. 2. Check and replace as necessary.
B.3. Defective thermostat control or 3. Replace thermostat or
COMPRESSORpressure switch. pressure switch.
CLUTCH4. Shorted or open field coil. 4. Replace coil.
INOPERATIVE5. Bearing seized (clutch will not 5. Replace clutch pulley assembly.
disengage).
6. Refrigeration circuit problem causing
heavy load and excessive drive
torque.6. Check and rectify.
1. Incorrect alignment. 1. Check alignment; repair as
necessary.
2. Loose belt. 2. Adjust to proper tension.
C.3. Compressor not mounted securely. 3. Repair as necessary.
COMPRESSOR4. Bearing in clutch-pulley 4. Remove clutch and replace
CLUTCHassembly not pressed in. clutch pulley assembly.
NOISY5. Low voltage to clutch. 5. Check connections and voltage.
6. Clutch will not spin freely. 6. Refer to B5 above.
7. Oil on clutch face. 7. Check compressor seals for leaks.
8. Slipping clutch. 8. Refer to C5 above. Then check air
gap.
9. Overloaded or locked compressor. 9. Repair or replace compressor.
10. Icing. 10. Check for suction line frosting.
Replace expansion valve if
necessary.
Replace receiver/drier if necessary.
D.1. Motor and/or blades improperly 1. Check mountings, adjust as
CONDENSERmounted. necessary.
VIBRATION2. Foreign matter build-up on 2. Clean blades with a suitable
blades. non-inflammable cleaner.
3. Excessive wear of motor bearings. 3. Replace motor.

82AIR CONDITIONING
20
REPAIR THERMOSTAT - REAR
Service repair no - 82.26.09
Remove
1.Remove evaporator/blower motor assembly
harness.
See harness - evaporator/blower
motor assembly - rear
2.Remove foam seal from evaporator to alpine
light duct flange.
3.Remove screws securing 2 relay mounting
brackets to evaporator/blower motor casing and
position aside.
4.Disconnect 2 Lucars from thermostat.
5.Loosen 2 screws securing thermostat.
6.Release thermostat from bracket.
7.Remove 2 clips securing evaporator/blower
motor casing halves.
8.Remove screw securing evaporator/blower
motor casing halves.
9.Separate casing sufficiently to enable removal of
thermostat probe from casing.
10.Remove thermostat.
Refit
11.Position thermostat fixings to casing and tighten
screws.
12.Connect Lucars to thermostat.
13.Separate casing sufficiently to enable fitment of
thermostat probe to casing.
14.Fit and tighten screw securing casing halves.
15.Fit clips securing casing halves.
16.Remove backing paper from NEW foam,
evaporator to alpine light duct, flange seal.
17.Fit foam seal to evaporator/blower motor casing
flange.
18.Fit evaporator/blower motor assembly harness.
See harness - evaporator/blower motor
assembly - rear; Refit

AIR CONDITIONING
21
REPAIR HARNESS - EVAPORATOR/BLOWER MOTOR
ASSEMBLY - REAR
Service repair no - 82.26.12
Remove
1.Remove evaporator/blower motor assembly.
See evaporator/blower motor assembly -
rear
2.Remove screw securing harness retaining clip to
casing.
3.Release harness clip from casing tag.
4.Disconnect 4 relay multiplugs.
5.Disconnect 2 Lucars from thermostat.
6.Disconnect multiplug from ECU.
7.Release control valve solenoid multiplug from
mounting bracket and disconnect multiplug.
8.Disconnect multiplug from blower motor.
9.Disconnect multiplug from resistor.
10.Remove harness.Refit
11.Fit harness and route into position.
12.Connect multiplug to resistor.
13.Connect multiplug to blower motor.
14.Connect control valve solenoid multiplug and
secure multiplug to mounting bracket.
15.Connect multiplug to ECU.
16.Connect Lucars to thermostat.
17.Connect multiplugs to relays.
18.Secure harness clip to casing tag.
19.Fit screw securing harness retaining clip to
casing.
20.Fit evaporator/blower motor assembly.
See
evaporator/blower motor assembly - rear;
Refit