clutch LAND ROVER DISCOVERY 1995 Service Owner's Manual

19FUEL SYSTEM
6
DESCRIPTION AND OPERATION DESCRIPTION ELECTRONIC DIESEL CONTROL
The Electronic Diesel Control (EDC) 'drive by wire'
system derives its from the replacement of
conventional mechanical controls by electronic
components.
The EDC system supplies the exact amount of fuel to
the engine according to the prevailing engine
operating conditions. To monitor these conditions,
sensors are fitted to the engine to measure engine
parameters. Data from the sensors is received by the
Engine Control Module (ECM) which determines the
exact amount of fuel, injection timing and Exhaust
Gas Recirculation (EGR) required for any running
condition.
Safety and emergency features are built into the
system which protect the engine against overspeed
and overheating damage. In the event of component
failure the system is designed to compensate and
allow emergency start and limp home facilities to
operate. The ECM does this by substituting a default
value for the failed component which may result in a
noticeable loss in power but keeps the engine
running.FUEL SYSTEM COMPONENT LOCATION EDC
1. Vehicle speed sensor
2. No. 4 injector sensor
3. Coolant temperature sensor
4. Boost pressure sensor
5. Electro-pneumatic modulator
6. Airflow sensor
7. Engine speed sensor
8. Brake/clutch switches
9. Injector pump
10. Throttle position sensor
11. Engine control module

19FUEL SYSTEM
8
DESCRIPTION AND OPERATION FUEL SYSTEM LAYOUT EDC
1. Fuel injection pump
2. Fuel temperature sensor
3. Air temperature sensor
4. Water temperature sensor
5. No. 4 injector sensor
6. Air flow sensor
7. Engine speed sensor
8. Boost pressure sensor
9. Vehicle speed sensor
10. Clutch switch
11. Brake switch
12. Throttle position sensor
13. Electro-pneumatic modulator
14. Exhaust gas recirculation (EGR) valve
15. Engine control module (ECM)
16. Diagnostic indicator
A. To turbo
B. To air box.
C. To 'T' piece on brake servo hose position
D. Solenoid operated valve energization timing device.
E. Fuel cut off
F. Actuator current
G. Control collar

19FUEL SYSTEM
10
DESCRIPTION AND OPERATION Vehicle speed sensor
The vehicle speed sensor is located on the transfer
box behind the transmission brake. The unit has a
multirole as the vehicle electronic speedometer
sensor and as a sensor for 'surge damping', (a
function which smooths out engine response to sharp
accelerator movement and reduces vehicle 'bucking').
The sensor is an additional input for engine overheat
protection.
Brake and clutch switches
The brake and clutch switches are located on the
pedal box and serve as safety features to the system.
They return information to the ECM which limits
maximum fuel quantity under braking.
Throttle position sensor
The accelerator pedal is connected directly to a
sensor mounted in the pedal box. Driver demand is
relayed back to the ECM to increase or decrease
injected fuel quantity.
Incorporated in the sensor is a backup idle switch
which the system will default to in the event of sensor
failure.
Boost pressure sensor
The boost pressure sensor is mounted on the
bulkhead. It relays boost pressure information to the
ECM which compensates fuel quantity to reduce
smoke during acceleration.
Electro-pneumatic modulator
The electro-pneumatic modulator is located on the
inner wing just forward of the air cleaner. It regulates
vacuum signals from the source to the EGR valve.
The ECM controls the modulator to open the EGR
valve according to required airflow.Exhaust gas recirculation valve
The EGR valve is located on the engine exhaust
manifold and is controlled by vacuum from the
electro-pneumatic modulator.
Once open the EGR valve directs a quantity of
exhaust gas back into the inlet manifold to be burnt
inside the engine. This reduces NOx (Oxides of
nitrogen) emissions of the engine.
Temperature sensors
Water, Fuel and Air temperature sensors monitor
engine conditions and relay their information back to
the ECM which makes adjustments to injected fuel
quantity, injection timing, EGR and corrections to
measured boost pressure and airflow.

Tdi
17
REPAIR VEHICLE SPEED SENSOR
Service repair no - 18.30.22
Remove
NOTE: The following procedure is carried
out with the ramp still raised.
1.Disconnect battery negative lead.
2.Disconnect sensor multi-plug.
3.Remove sensor retaining screw.
4.Remove sensor retaining plate.
5.Remove sensor from transfer box.
Refit
6.Reverse removal procedure.CLUTCH PEDAL SWITCH
Service repair no - 18.30.67
Remove
1.Disconnect battery negative lead.
2.Disconnect switch wiring lucars.
3.Turn rear body of switch to release locknut
4.Remove locknut.
5.Remove switch from mounting bracket.
Refit
6.Reverse removal procedure.

19FUEL SYSTEM
2
DESCRIPTION AND OPERATION CRUISE CONTROL SYSTEM - V8i/Tdi AUTO EDC
Description
The cruise control system consists of
electro-mechanical devices, and comprises of the
following components.
ELECTRONIC CONTROL UNIT (ECU)
The microprocessor based ECU evaluates the signals
provided by the driver controls, brake pedal switch,
clutch pedal switch on manual models, and the
vehicle speed sensor. The ECU activates the vacuum
pump as required. The ECU also has a memory
function for set speed storage.
Driver operated switches
The main cruise control switch is located in the
auxiliary switch panel and activates the cruise control
system. The steering wheel switches provide
'set/accelerate' and 'resume/decelerate' features.
These switches provide the interface between driver
and cruise control system.
Brake pedal switch
The brake pedal switch is located under the lower
dash attached to the brake pedal mounting bracket.
The switch provides for fast disengagement of the
cruise control system and rapid return of the throttle
levers to the idle position when the brake pedal is
applied.
Clutch pedal switch
The clutch pedal switch is located under the lower
dash attached to the clutch pedal mounting bracket.
The switch provides for fast disengagement of the
cruise control system and rapid return of the throttle
levers to the idle position when the clutch pedal is
applied.Vehicle speed sensor
The vehicle speed sensor is located on the side of the
transfer box adjacent to park brake. The sensor
provides road speed data to the ECU. The cruise
control system cannot be engaged until the road
speed exceeds 45 km/h, (28 mph) the system will
automatically disengage at a road speed of 42 km/h
(26 mph).
Vacuum pump
The vacuum pump is energised when the main cruise
control switch is operated, and is actuated by the
steering wheel and brake pedal switches. The pump
provides a vacuum source to the cruise control
actuator. A control valve in the pump provides for
steady increase of road speed or purge of the system
when the brake pedal is applied.
Actuator
The actuator provides the servo mechanism link
between the cruise control system and throttle linkage
and is operated by vacuum from the vacuum pump.
Neutral lockout relay - automatic vehicles
The relay module is located in the right hand side
footwell, accessible by removing the trim casing.
The function of the relay module is to disengage the
cruise control system if neutral, or park, is selected in
the main gearbox, when the system is engaged.
Engine speed trip ECU - Manual vehicles
This unit is located in the right hand side footwell,
accessible by removing the trim casing.
The function of the unit is to disengage cruise control
if engine speed exceeds 5000 rev/min.

CRUISE CONTROL
1
FAULT DIAGNOSIS ROAD TEST
CAUTION: Do not engage cruise control
when vehicle is being used in low transfer
gear or reverse.
WARNING: The use of cruise control is not
recommended on winding, snow covered
or slippery roads or in heavy traffic
conditions where a constant speed cannot be
maintained.
1.Start engine, depress main control switch to
actuate cruise control system. Accelerate to
approximately 50 km/h, (30 mph), operate
'set/acc'switch, immediately release switch,
remove foot from accelerator pedal. Vehicle
should maintain speed at which'set/acc'switch
was operated.
2.Operate'set/acc'switch and hold at that
position, vehicle should accelerate smoothly until
switch is released. Vehicle should now maintain
new speed at which'set/acc'switch was
released.
3.Momentarily touch and release'set/acc'switch,
vehicle speed should increase 1.6 km/h (1 mph)
for each touch. Note that five touches will
increase speed 8 km/h (5 mph).
4.Apply'res/decel'switch while vehicle is in cruise
control mode, cruise control should disengage.
Slow to approximately 55 km/h, (35 mph)
operate'res/decel'switch, immediately release
switch and remove foot from accelerator, vehicle
should smoothly accelerate to previously set
speed. Increase speed using accelerator pedal,
release pedal, vehicle should return to previously
set speed.
NOTE: The cruise control system fitted to
the diesel engine is not as responsive as
that fitted to the petrol engine, due to the
characteristics of diesel engines. Therefore, at
speeds below approx. 65 km/h (40 mph), the
vehicle speed may drop when cruise is selected
and then slowly regain the 'set' speed.5.Operate brake pedal, cruise control system
should immediately disengage returning vehicle
to driver control at accelerator pedal. Operate
'res/decel'switch, vehicle should accelerate to
previously set speed without driver operation of
accelerator pedal.
6.Operate'res/decel'switch and allow vehicle to
decelerate to below 42 km/h, (26 mph). Operate
'res/decel'switch, cruise control system should
remain disengaged.
7.Operate'set/acc'switch below 40 km/h, (28
mph), cruise control system should remain
disengaged. Accelerate, using accelerator pedal
to above 45 km/h, (28 mph), operate'res/decel'
switch, and remove foot from accelerator pedal,
vehicle should smoothly adjust to previously
memorised speed.
8. Automatic vehicles- select neutral, system
should disengage.Manual vehicles- depress
clutch, system should disengage.
9.Cruise at 80 km/h (50 mph), declutch, select
neutral, remove foot from clutch. Operate
'res/decel'switch. Engine should rev to 5000
rev/min, cruise control disengages, engine
returns to idle.
10.Engage forward gear. Operate'res/decel'
switch. Remove foot from accelerator. Speed
should accelerate to previous set speed.
11.Depress main control switch in control system
should immediately disengage and erase
previously set speed from ECU memory.
See
Electrical Trouble Shooting Manual.
ELECTRICAL TESTS
Electrical functionality can be checked using
TestBook.
CABLE SETTING - TDi AUTOMATIC MODELS
1.An incorrectly adjusted kickdown cable can
prevent correct operation of the cruise control
system.
See AUTOMATIC GEARBOX,
Adjustment, kickdown cable adjustment.

CRUISE CONTROL
1
REPAIR BRAKE AND CLUTCH PEDAL SWITCHES/VENT
VALVES
Service repair no - 19.75.34 - Clutch Switch
Service repair no - 19.75.35 - Brake Switch
Remove
1.Remove 3 studs securing driver's side fascia
closing panel.
2.Release and move closing panel aside.
3.Locate and release locking sleeve.
4.Release switch/vent valve from pedal bracket.
5.Disconnect vacuum hose and harness connector
from switch.
6.Remove switch.
Refit
7.Reverse removal procedure.
NOTE: Ensure locking sleeve is correctly
positioned.

CLUTCH
1
DESCRIPTION AND OPERATION DESCRIPTION
The clutch unit fitted with the manual transmission,
comprises a single dry plate friction disc and
diaphragm spring clutch unit, secured to the engine
flywheel.OPERATION
The unit is operated hydraulically by the clutch master
cylinder 12 and a slave cylinder 13 attached to the
transmission bell housing.
1. Crankshaft and flywheel
2. Friction plate
3. Clutch cover
4. Diaphragm spring
5. Pressure plate
6. Fulcrum posts (9) for diaphragm spring
7. Bearing rings (2) for diaphragm spring
8. Retraction links and bolts (3) for pressure plate
9. Release bearing
10. Release lever11. Release lever pivot post
12. Master cylinder
13. Slave cylinder
14. Master cylinder pedal pushrod
15. Primary shaft and taper bearing (in gearbox)
16. Gearbox front cover
17. Primary shaft flywheel bush
18. Pedal pivot and return spring
19. Hydraulic damper (Diesel only)

33CLUTCH
2
DESCRIPTION AND OPERATION When the clutch pedal is depressed, hydraulic fluid
transmits the movement via the slave cylinder, release
lever 10, bearing 9, to the inner fingers of the
diaphragm spring 4.
The diaphragm spring 4 pivots on the bearing rings 7
and fulcrum posts 6 causing the pressure plate 5 to
release the clamping force on the friction plate and
linings 2.As the the clamping force is removed from the friction
plate 2, the plate slides on the splines of the primary
shaft 15 and takes up a neutral position between the
flywheel 1 and the pressure plate 5 , thus breaking the
drive between the engine and the gearbox.
NOTE: Diesel engined vehicles have an
hydraulic damper 19 fitted into the system.
The damper contains a steel diaphragm
which absorbs slight hydraulic pulses caused by
cyclic variations of the diesel engine crankshaft at
low rpm.

CLUTCH
1
FAULT DIAGNOSIS CLUTCH ASSEMBLY CONDITIONS
For the clutch to operate correctly as described and
illustrated in the "Description and Operation", it is
important the following conditions are satisfied:-
A. The primary shaft 15 must be free in the
crankshaft spigot bush 17.
B. The friction plate 2 must be able to slide easily
on the splines on the primary shaft 15, to a
position where it does not contact either the
flywheel or the pressure plate.
C. The friction plate must not be distorted or the
linings contaminated with oil, which may cause it
to stick or continue to run in contact with the
flywheel or pressure plate.
A number of faults can develop in the operation of the
clutch for a variety of reasons and although most
faults are due to normal wear at high mileage,
problems can also occur if the unit has been renewed
by an unskilled operator.
Recognising and diagnosing a particular clutch fault is
therefore of paramount importance in ensuring, that
the problem is rectified at the first attempt.
Problems which develop in the clutch are as follows:-
A. Clutch spin/drag
B. Clutch slip
C. Clutch judder/fierceCLUTCH SPIN - DRAG
Symptoms
Clutch spin is that, with engine running and clutch
pedal depressed, the gears cannot be immediately
engaged without making a grinding noise. This
indicates the clutch is not making a clean break.
However, if the clutch pedal is held depressed for
several seconds the friction plate will eventually break
free from the engine and the gear will engage silently.
Clutch spin as it becomes more severe develops into
clutch drag, making the silent engagement of a gear
impossible, regardless of how long the pedal is held
depressed.
CLUTCH SLIP
Symptoms
Clutch slip is most evident climbing a hill or when the
vehicle is moving off from stationary with a heavy
load. As the clutch is released slip occurs between the
engine and the transmission, allowing the engine
speed to increase without a corresponding increase in
vehicle speed.
Clutch slip can develop to the stage where no power
is transmitted through the clutch as the pedal is
released.
CLUTCH JUDDER - FIERCE
Symptoms
Clutch judder or fierce engagement, like slip, is most
likely to occur when the vehicle is moving off from
stationary. As the clutch pedal is released the vehicle
will move rapidly or in a series of jerks, which can not
be controlled even by careful operation of the clutch
by the driver.
It should be noted that a vehicle may display all the
symptoms or any combination of the symptoms
described, depending on the driving conditions vehicle
load and operating temperatures.