cooling LAND ROVER DISCOVERY 2002 Repair Manual

ENGINE MANAGEMENT SYSTEM - TD5
18-1-56 REPAIRS
Intercooler
$% 19.42.15
Remove
1.Remove cooling fan and coupling.

+ COOLING SYSTEM - Td5, REPAIRS,
Fan - viscous.
2.Remove battery.
3.Remove vehicle jack from battery carrier.
4.Remove screw and release engine control
module (ECM) from battery carrier.
5.Remove 7 bolts and remove battery carrier. 6.Remove 2 screws and remove lower half of fan
cowl.
7.Remove front grille.

+ EXTERIOR FITTINGS, REPAIRS,
Grille - front - up to 03MY.
8.Remove 6 scrivets and remove LH and RH air
deflectors from front panel.

ENGINE MANAGEMENT SYSTEM - TD5
18-1-58 REPAIRS
3.Fit brackets with rubber mountings to
intercooler and fit and tighten screws securing
brackets to condenser.
4.Fit radiator upper mounting brackets and
tighten bolts.
5.Fit LH horn and secure with nut.
6.Connect inlet and outlet hoses to intercooler
and tighten clips.
7.Fit lower half of fan cowl and secure with
screws.
8.Fit LH and RH air deflectors to front panel and
secure with scrivets.
9.Fit front grille.
10.Fit battery carrier and secure with bolts.
11.Fit ECM and secure with screw.
12.Fit jack to battery carrier.
13.Fit battery.
14.Fit cooling fan and coupling.

+ COOLING SYSTEM - Td5, REPAIRS,
Fan - viscous.
Valve - solenoid boost control
$% 19.42.30
Remove
1.Loosen clip and release air intake hose from
MAF sensor.
2.Release clips and disconnect vacuum hoses
from solenoid valve.
3.Disconnect multiplug from solenoid valve.
4.Remove 2 bolts and remove solenoid valve.
Refit
1.Position solenoid valve and tighten bolts.
2.Connect multiplug to solenoid valve.
3.Connect vacuum hoses and secure with clips.
4.Position air intake hose to MAF sensor and
secure clip.

ENGINE MANAGEMENT SYSTEM - TD5
REPAIRS 18-1-61
Injectors
$% 19.60.12
Remove
1.Remove cooling fan.

+ COOLING SYSTEM - Td5, REPAIRS,
Fan - viscous.
2.Remove rocker shaft.

+ ENGINE - Td5, REPAIRS, Rocker
shaft assembly.
3.Position container to catch fuel spillage.
4.Disconnect quick release fuel hose connectors
from fuel connector block on cylinder head and
fuel cooler to drain fuel from cylinder head. 5.Disconnect 5 multiplugs from injectors.
6.Remove 5 Torx bolts securing injectors to
cylinder head.
7.Using LRT-12-154/1, remove injectors from
cylinder head. Collect retainers.
8.Using LRT-12-154/4, remove sealing washers
from injectors. Discard sealing washers.
9.Remove and discard 'O' rings from injectors.
10.Rotate engine manually until each cylinder
being worked on is at TDC, and remove excess
fuel from piston bowl using a syringe.

ENGINE MANAGEMENT SYSTEM - TD5
18-1-62 REPAIRS
Refit
1.Clean injector units and mating faces in
cylinder head.
2.Using LRT-12-154/2, fit a new 'O' ring to each
injector.
3.Using LRT-12-154/3, fit a new sealing washer
to each injector.
4.Fit retainer to injector. Carefully fit injector,
ensuring retainer is located on its dowel, and
tighten Torx bolt to 32 Nm (24 lbf.ft)
5.Connect multiplug to injector.
6.Repeat above operations for remaining
injectors.
7.Connect fuel hoses to connector block and fuel
cooler.
8.Programme new injectors using TestBook.
9.Fit rocker shaft.

+ ENGINE - Td5, REPAIRS, Rocker
shaft assembly.
10.Fit cooling fan.

+ COOLING SYSTEM - Td5, REPAIRS,
Fan - viscous.
Switch - cruise control (on/off)
$% 19.75.30
Remove
1.Carefully remove switch from instrument cowl.
2.Disconnect multiplug and remove switch.
Refit
1.Position new switch and connect multiplug.
2.Carefully push switch into instrument cowl.

ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-3
Engine management component
location - Engine compartment
1Mass air flow/ inlet air temperature sensor
2Fuel injectors
3High tension leads/spark plugs
4Fuel pump relay
5ATC compressor clutch relay/ cooling fan relay
6Throttle position sensor
7Heated oxygen sensor
8Idle air control valve
9Ignition coils
10Engine coolant temperature sensor
11Crankshaft speed and position sensor
12Knock sensor
13Camshaft position sensor

ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-5
1Engine control module
2Crankshaft speed and position sensor
3Camshaft position sensor
4Engine coolant temperature sensor
5Mass air flow/ inlet air temperature sensor
6Throttle position sensor
7Heated oxygen sensors
8Fuel injectors
9Idle air control valve
10Fuel pump relay
11EVAP canister
12EVAP canister vent valve
13EVAP canister purge valve
14Fuel tank pressure sensor
15Ignition coils
16Knock sensor
17Spark plugs
18High/ Low ratio switch
19Malfunction indication lamp
20Diagnostic connector
21Air temperature control clutch relay
22Air temperature control cooling fan relay
23ATC ECU
24CAN link to EAT
25SLABS ECU
26BCU
27Instrument cluster
28Thermostat monitoring sensor (where fitted)

ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-17
The ECT sensor can fail the following ways or supply incorrect signal:
lSensor open circuit.
lShort circuit to vehicle supply.
lShort circuit to earth.
lIncorrect mechanical fitting.
lSignal fixed above 40
°C (140 °F) will not be detected.
lSignal fixed below 40
°C (140 °F) will be detected.
In the event of an ECT sensor signal failure any of the following symptoms may be observed:
lDifficult cold start.
lDifficult hot start.
lDriveability concern.
lMIL illuminated.
lInstrument cluster temperature warning lamp illuminated.
lTemperature gauge reads excessively hot.
lTemperature gauge reads excessively cold.
lCooling fan will not run.
There are three types of ECT sensor diagnostic checks:
lThe ECT sensor signal is within limits, but is inaccurate – the engine has to be running and the signal indicates
a coolant temperature below 40
°C (104°F). The signal differs too much from the coolant temperature model for
longer than 2.53 seconds.
lThe ECT sensor signal is greater than the maximum threshold value – the ECM has to be powered up to perform
the diagnostic, but the engine does not need to be running.
lThe ECT sensor signal is less than the minimum threshold value – the ECM has to be powered up to perform
the diagnostic, but the engine does not need to be running.
Should a malfunction of the component occur the following fault codes may be evident and can be retrieved by
TestBook:
P code J2012 description Land Rover description
P0116 Engine coolant temperature circuit/range
performance problemSignal differs too much from temperature model for
longer than 2.53s
P0117 Engine coolant temperature circuit low input Open circuit or short circuit to battery supply
P0118 Engine coolant temperature circuit high input Short circuit to earth

ENGINE MANAGEMENT SYSTEM - V8
18-2-24 DESCRIPTION AND OPERATION
Air intake duct – Gulf models from 2000MY
1Heat reflective insulation
2Supplementary air intake duct
The density of the intake air is partly dependent on altitude and temperature. Hot air has a lower density than cold air;
consequently in hot climates, the low air density can result in low power due to low volumetric efficiency.
In order to improve engine performance, Gulf specification models from 2000MY have a secondary air intake duct
which is located under the front left inner wing of the vehicle. Cooler air from the side of the vehicle is routed through
the duct to the air cleaner, where it combines with air entering via the front grille.
In addition to the secondary air duct, the vehicles are fitted with a larger front grille and have larger cooling and
condenser fans.
The MAF/IAT sensor, air cleaner and air cleaner duct are encased in insulation bags to help keep the intake air cool
and so increase the mass of air entering the engine intake manifold.
The air cleaner includes a cyclone filter and also a dump valve in the bottom of the unit. Sand and dust particles which
are carried into the air cleaner with the air flow are automatically expunged via the dump valve.
M180452
1
2

ENGINE MANAGEMENT SYSTEM - V8
18-2-42 DESCRIPTION AND OPERATION
Cooling fan relay
The cooling fan relay is located in the engine compartment fuse box. It is a four pin normally open relay. The relay
must be energised to drive the cooling fan.
The cooling fan is used to cool both the condenser in which the ATC refrigerant is held and the radiator. This fan is
used especially when the engine is operating at excessively high temperatures. It is also used as a part of the ECM
backup strategy if the ECT fails.
Input/Output
The ECM provides the earth for the relay coils to allow the relay contacts to close and the cooling fan motor to receive
battery voltage. The ECM uses a transistor as a switch to generate an open circuit in the earth path of the relay
windings. When the ECM opens the earth path, the return spring in the relay will pull the contacts apart to shut down
the cooling fan motor drive.
Input to the cooling fan relay switching contacts is via fuse 5 located in the engine compartment fuse box. The relay
coils are supplied with battery voltage from the main relay, also located in the engine compartment fuse box. The earth
path for the relay coils is via pin 31 of the ECM connector C0636. When the relay is energised the output from the
switching contacts is directly to the cooling fan motor.
The cooling fan relay can fail in the following ways:
lRelay open circuit.
lShort circuit to vehicle battery supply.
lShort circuit to vehicle earth.
lBroken return spring.
In the event of a cooling fan relay failure, the cooling fan does not work.

ENGINE MANAGEMENT SYSTEM - V8
18-2-46 DESCRIPTION AND OPERATION
Idle speed control
The ECM regulates the engine speed at idling. The ECM uses the idle air control valve (IACV) to compensate for the
idle speed drop that occurs when the engine is placed under greater load than usual. When the throttle is in the rest
position i.e. it has not been pressed, the majority of intake air that the engine consumes comes from the idle air control
valve.
IACV control idle speed
Conditions in which the ECM operates the IACV control idle speed is as follows:
lIf any automatic transmission gears other than P or N are selected.
lIf air conditioning is switched on.
lIf cooling fans are switched on.
lAny electrical loads activated by the driver.
Function
The idle air control valve utilises two coils that use opposing pulse width modulated (PWM) signals to control the
position of a rotary valve. If one of the circuits that supplies the PWM signal fails, the ECM closes down the remaining
signal preventing the idle air control valve from working at its maximum/ minimum setting. If this should occur, the idle
air control valve assumes a default idle position at which the engine idle speed is raised to 1200 rev/min with no load
placed on the engine.
Evaporative emission control
Due to increasing legislation, all new vehicles must be able to limit evaporative emissions (fuel vapour) from the fuel
tank.
The ECM controls the emission control system using the following components:
lEVAP canister.
lPurge valve.
lCanister vent solenoid (CVS) valve – (NAS vehicles with vacuum type EVAP system leak detection capability
only)
lFuel tank pressure sensor – (NAS vehicles with vacuum type EVAP system leak detection capability only)
lFuel leak detection pump – (NAS vehicles with positive pressure type EVAP system leak detection capability
only)
lInterconnecting pipe work.
Refer to Emissions section for operating conditions of evaporative emission systems.

+ EMISSION CONTROL - V8, DESCRIPTION AND OPERATION, Evaporative emission control operation.
On-Board Diagnostics (OBD) - North American Specification vehicles only
The ECM monitors performance of the engine for misfires, catalyst efficiency, exhaust leaks and evaporative control
loss. If a fault occurs, the ECM stores the relevant fault code and warns the driver of component failure by illuminating
the Malfunction Indicator Light in the instrument pack.
On vehicles fitted with automatic gearbox, the ECM combines with the Electronic Automatic Transmission (EAT) ECU
to provide the OBD strategy.
Conditions
If the OBD function of the ECM flags a fault during its operation, it falls into one of the following categories:
lmin = minimum value of the signal exceeded.
lmax = maximum value of the signal exceeded.
lsignal = signal not present.
lplaus = an implausible condition has been diagnosed.