ignition system LAND ROVER DISCOVERY 1995 Service Manual

19FUEL SYSTEM
10
DESCRIPTION AND OPERATION
Driving
When the throttle pedal is depressed, the ECM
implements the cruise air/fuel ratio map. During
driving the ECM continually monitors inlet air
temperature and engine speed and load for it's air
flow calculations, together with coolant temperature
for any temperature corrections. Additional inputs are
throttle potentiometer for acceleration and throttle
pedal switch for cruise/idle fuel map selection and
over-run fuel cut-off.
Acceleration enrichment
When the throttle pedal is depressed, the ECM
receives a rising voltage from the throttle
potentiometer and detects a rise in manifold pressure
from the manifold absolute pressure sensor. The ECM
provides additional fuel by increasing the normal
injector pulse width and also provides a small number
of extra injector pulses on rapid throttle openings.
Over-run fuel cut-off
The ECM implements over-run fuel cut-off when the
following signals are received.
·Throttle disc closed.
·Engine speed is above 2000 rev/min - engine at
normal operating temperature.
Fuel is reinstated progressively when any of the
above signals cease.
Over-speed fuel cut-off
To prevent damage at high engine speeds the ECM
inhibits the earth path for the injectors, cutting off
injection. As engine speed falls, injection is reinstated.
Ignition switch off
When the ignition is switched off, the ECM will keep
the main relay energised for approx. 30 seconds while
it drives the stepper motor to the 35 step position for
the next engine start.

V8i
1
FAULT DIAGNOSIS ENGINE OVERHEATING
Before conducting any cooling system diagnosis:
See
Description and operation, Engine Cooling
1.Is coolant level correct?
NO - Allow engine to cool, top up level to
expansion tank seam.
YES - Continue.
2.Is drive belt tension correct?
NO -
See ENGINE, Repair, Drive Belt -
Check Tension
YES - Continue.
3.Is ignition timing correct?
NO -
See ELECTRICAL, Adjustment,
Ignition Timing
YES - Continue.
4.Is coolant in radiator frozen?
YES - Slowly thaw and drain system.
See
Adjustment, Coolant Requirements
NO - Continue.
5.Is air flow through radiator restricted or blocked?
YES - Apply air pressure from engine side of
radiator to clear obstruction.
NO - Continue.
6.Are there any external leaks, from water pump,
engine gaskets or the heater unit?
YES - Investigate and rectify.
See Adjustment,
Coolant Requirements
NO - Continue.
7.Are fan blades fitted correct way round, concave
side towards engine?
NO - Rectify.
YES - Continue.8.Is viscous unit operating correctly?
See
Description and operation, Viscous Fan
NO - Renew.See Repair, Viscous
Coupling, Fan Blades, Pulley and Fan
Cowl
YES - Carry out a pressure test on radiator cap
and system. Check thermostat type,
operation and correct fitting
See Repair,
Thermostat
If pressure test leads you to suspect coolant
leakage across gaskets, go to check 11,
otherwise: Continue.
9.Are the air conditioning fans operating correctly?
See Electrical Trouble Shooting Manual.K5
NO - Rectify.
YES - Continue.
10.Is temperature sender and gauge giving
accurate readings?
NO - Substitute parts and compare readings.
YES - Continue.
11.Carry out cylinder pressure test to determine if
pressure is leaking into cooling system causing
over pressurising and loss of coolant.
If problem is not diagnosed, check the coolant system
for engine oil contamination and engine lubrication
system for coolant contamination.
If the coolant only, or both systems are contaminated,
suspect cylinder head gaskets or radiator.
If only the lubrication stystem is contaminated with
coolant, suspect inlet manifold or front cover gaskets.

57STEERING
12
REPAIR UPPER STEERING COLUMN
Service repair no - 57.40.01
NOTE: Steering column assembly is not a
serviceable component.
CAUTION: Before removing any parts of
steering linkage, it is imperative that road
wheels are positioned straight ahead. then
steering wheel removed to prevent rotary coupler
being wound up or damaged.
CAUTION: After refitting steering linkage
parts follow correct procedure to ensure
that road wheels, steering box and
steering wheel are correctly positioned relative to
each other when in straight ahead condition. if
steering wheel requires repositioning, ensure that
drive pegs on rotary coupler are correctly
positioned before steering wheel is replaced.
This ensures drive pegs locate in their holes in
rear of steering wheel.
After final alignment, connect rotary coupler
multiplug, tighten steering wheel securing nut and
fit airbag - if fitted or steering wheel trim pad and
horn push assembly.
Remove
1.Remove steering wheel.
See Steering Wheel
CAUTION: Prevent rotation of rotary
coupler once steering wheel is removed.
Secure in position with adhesive tape.
2.Remove driver's access panel.
3.Remove steering column shroud.
See Steering
Column Shroud
4.Remove rotary coupler.See
SUPPLEMENTARY RESTRAINT SYSTEM,
Repair, Rotary Coupler
5.If fitted - remove 4 screws securing knee bolster,
remove knee bolster.
6.Disconnect column switch multiplug.
7.Disconnect ignition switch multiplug from fuse
box.

57STEERING
14
REPAIR Refit
20.Manoeuvre upper column to position in footwell,
ensure splines in column and universal joint are
correctly engaged and rubber boot is fitted.
21.Fit but do not tighten universal joint pinch bolt.
22.Position upper column to upper mounting, fit
washers and nuts, do not tighten nuts.
23.Fit but do not tighten nuts and bolts securing
upper column to lower mounting.
24.Fit lower mounting steady bracket, fit but do not
tighten nuts and bolts.
25.Ensure upper column is aligned to mountings.
26.Tighten all nuts and bolts to
22 Nm.
27.Tighten universal joint pinch bolt to25 Nm.
28.Connect column switch multiplug.
29.Connect ignition switch multiplugs.
30.Fit rotary coupler.
See SUPPLEMENTARY
RESTRAINT SYSTEM, Repair, Rotary
Coupler
31.Fit steering wheel.See Steering Wheel
32.Reconnect battery negative lead.
33.Check steering column lock for correct
operation, tighten shear bolts until heads shear
off.
34.If fitted - position knee bolster, fit and tighten
screws.
35.Fit steering column shroud.
See Steering
Column Shroud
36.Fit driver's access panel.

SUPPLEMENTARY RESTRAINT SYSTEM
5
DESCRIPTION AND OPERATION
7.Do not use electrical test equipment on the
airbag harness or connectors. Tampering with or
disconnecting the harness could result in
accidental firing of the airbag or make the
system inoperative, which may result in serious
injury.
8. An airbag system fault can only be
diagnosed using TestBook.
9.The airbag module contains Sodium Azide which
is poisonous and extremely flammable. Contact
with water, acid or heavy metals may produce
harmful or explosive compounds. Do not
dismantle, incinerate or bring into contact with
electricity.VEHICLE RECOVERY
Towing - airbag not deployed
Normal towing procedures are unlikely to cause an
airbag to deploy. However, as a precaution switch the
ignition off and then disconnect both battery leads.
Disconnect the negative '-' lead first.
Towing - airbag deployed
Once the driver's airbag has been deployed the
vehicle must have a front suspended tow. However,
as a precaution switch the ignition off and then
disconnect both battery leads. Disconnect the
negative '-' lead first.

SUPPLEMENTARY RESTRAINT SYSTEM
1
REPAIR SYSTEM PRECAUTIONS
CAUTION: Before and during any removal
operations within the SRS section, note
routing and position of all harnesses to aid
correct refitting and to avoid accidentally trapping
cables.
CAUTION: During refitting of any item
within the SRS section, always ensure
connectors are fully engaged and latched
before proceeding to the next stage of the
operation.DRIVER'S AIRBAG MODULE
Service repair no - 76.74.01
WARNING: All the airbag system
components, including the wiring harness,
MUST be renewed after the airbags have
deployed.
Remove
1.Turn steering wheel 90Ê from horizontal.
2.Switch off ignition.
3.Disconnect battery negative '-' and then the
positive '+' lead.
CAUTION: Always disconnect both leads.
4.Release 2 turnbuckles and remove dash lower
panel.

SUPPLEMENTARY RESTRAINT SYSTEM
9
REPAIR PASSENGER'S AIRBAG MODULE
Service repair no - 76.74.02
WARNING: All the airbag system
components, including the wiring harness,
MUST be renewed after the airbags have
deployed.
Remove
1.Switch off ignition.
2.Disconnect battery negative lead and then
positive lead.
3.Open glovebox and disconnect harness
connector from airbag module.
4.Use special socket and long extension, remove
2 torx head screws securing front of airbag
module to fascia panel.
5.Use special socket, remove 2 torx head screws
securing rear of airbag module to fascia panel.
6.Release airbag module from fascia panel.
CAUTION: Do not allow the airbag module
to hang by the airbag harness.
7.Carefully and without pulling on connector
remove airbag module.
CAUTION: Store the airbag module in
accordance with the storage procedures
described in Description and Operation.
NOTE: If airbag module is to be replaced
the serial number must be recorded in the
vehicle service record.
Refit
8.Reverse removal procedure.
9.Tighten airbag module securing screws to
8Nm
(6 lbf ft).
CAUTION: Take care not to cross thread
screws.
10.Check Supplementary Restraint System using
Testbook.

AIR CONDITIONING
5
DESCRIPTION AND OPERATION Condenser cooling fans
The condenser cooling fans operate automatically
whenever the air conditioning system is switched on.
Fan timer unit
The thermostatically controlled timer will continue to
operate the cooling fans after the air conditioning or
ignition is switched off. When the system temperature
is excessive, the fans will operate for 10 minutes to
reduce condenser and underbonnet temperature.
Blower control
The blower can be operated at any one of four speeds
by sliding the blower switch to the required position.
When the blower is switched off the air conditioning
system will not operate.
The fresh air/recirculation flaps can move between
two positions. One position covers the outside air
inlet, leaving open an inlet from the inside of the
vehicle clear, when recirculated air is required. In the
other position they will cover the inlet from the inside
of the vehicle leaving open the outside air inlet when
fresh air is required.Heater distribution and blend unit control
Blower unit air flow, having passed through the
evaporator passes into the heater blend unit to be
heated, if required. It is then directed into the vehicle
interior in accordance with the flap positions
designated by the air distribution control. Heater flaps
control the amount of air flowing through the heater
matrix. These flaps are controlled individually by the
driver's and passenger's temperature controls.
When the temperature control is in the cold position, a
micro switch actuates a vacuum control to close the
coolant valve on the engine. As the temperature
control is moved away from cold, the coolant valve is
opened allowing heated engine coolant to flow
throught the heater matrix. The temperature of the
heated air flow into the vehicle interior is controlled by
the blend flaps.
The distribution control moves the flaps which control
the direction of the air flow into the interior of the
vehicle.

82AIR CONDITIONING
6
ADJUSTMENT SYSTEM TEST
1.Place the vehicle in a ventilated, shaded area
free from excessive draught, with the doors and
windows open.
2.Check that the surface of the condenser is not
restricted with dirt, leaves, flies, etc. Do not
neglect to check the surface between the
condenser and the radiator. Clean as necessary.
3.Switch on the ignition and the air conditioner air
flow control. Check that the blower is operating
efficiently at low, medium and high speeds.
Switch off the blower and the ignition.
4.Check that the evaporator condensate drain
tubes are open and clear.
5.Check the tension of the compressor driving belt,
and adjust if necessary.
6.Inspect all connections for the presence of
refrigerant oil. If oil is evident, check for leaks,
and repair as necessary.
NOTE: The compressor oil is soluble in
Refrigerant R134a and is deposited when
the refrigerant evaporates from a leak.
7.Start the engine.
8.Set the temperature controls to cold and switch
the air conditioner blower control on and off
several times, checking that the magnetic clutch
on the compressor engages and releases each
time.9.With the temperature control at maximum
cooling and the blower control at high speed,
warm up the engine and fast idle at 1000
rev/min. Check the sight glass for bubbles or
foam. The sight glass should be generally clear
after five minutes running, occasional bubbles
being acceptable. Continuous bubbles may
appear in a serviceable system on a cool day, or
if there is insufficient air flow over the condenser
at a high ambient temperature.
10.Repeat at 1800 rev/min.
11.Gradually increase the engine speed to the high
range, and check the sight glass at intervals.
12.Check for frosting on the service valves.
13.Check the high pressure hoses and connections
by hand for varying temperature. Low
temperature indicates a restriction or blockage at
that point.
14.Switch off the air conditioning blower and stop
the engine.
15.If the air conditioning equipment is still not
satisfactory, carry out a pressure test as
previously described in this section.
COMPRESSOR DRIVE BELT
Service repair no - 82.10.01.
Tdi -
See ENGINE, Repair, Compressor drive belt
V8i and MpiSee ENGINE, Repair, Drive belt

84WIPERS AND WASHERS
2
DESCRIPTION AND OPERATION Wash wipe function
With the ignition switched on, power is supplied via a
fuse to the multi-switch, a control unit and a park
switch which is driven by the wiper motor.
Single wipe A
Pull the lever down and release immediately.
NOTE: With the lever held down, the
wipers will continue operating at high
speed until it is released.
Intermittent wipe B
Turn switch to second position.
Normal speed wipe C
Turn switch to second position.
Fast speed wide D
Turn switch to third position.
Variable delay (intermittent wipe)
Rotate the switch to vary the delay between wipes.
Windscreen washer E
Pull the lever towards the steering wheel. The
windscreen washers will operate in conjunction with
the wipers for as long as the lever is held in this
position.
Headlamp washers
The headlamp washers operate automatically
whenever the windscreen washers are operated,
provided the headlamps are illuminated and switched
to dipped beam. For continuous washing, hold the
windscreen washer control in the washposition E.
REAR WINDOW WIPER AND WASHER
OPERATION
The illustration J5375 also locates and identifies the
main components of the rear window wiper and
washer system which is operated by two switches
mounted on the right hand side of the instrument
binnacle.
Rear window wipe A
Press the switch to operate: after continuously wiping
3 or 4 times, the wiper operates intermittently (approx
once every 6 seconds) until switched off.
Rear window washer B
Press and hold the switch for the required duration of
rear screen washing. The wiper operates
automatically during washing and continues for a
further 3 wipes after the switch is released.