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Page 396 of 1672

LAND ROVER DISCOVERY 2002 Workshop Manual ENGINE MANAGEMENT SYSTEM - TD5
DESCRIPTION AND OPERATION 18-1-3
Engine management component
location - engine compartment
LHD illustrated
1Ambient air pressure sensor
2Engine coolant temperature sens

Page 398 of 1672

LAND ROVER DISCOVERY 2002 Workshop Manual ENGINE MANAGEMENT SYSTEM - TD5
DESCRIPTION AND OPERATION 18-1-5
1Mass air flow sensor
2Ambient air pressure sensor
3Manifold absolute pressure/ inlet air
temperature sensor
4Engine coolant temperatu

Page 399 of 1672

LAND ROVER DISCOVERY 2002 Workshop Manual ENGINE MANAGEMENT SYSTEM - TD5
18-1-6 DESCRIPTION AND OPERATION
Description
General
An engine control module (ECM) controls the five-cylinder direct injection diesel engine, and works on the drive by

ENGINE MANAGEMENT SYSTEM - TD5
18-1-6 DESCRIPTION AND OPERATION
Description
General
An engine control module (ECM) controls the five-cylinder direct injection diesel engine, and works on the drive by
wire principle. This means there is no throttle cable, the ECM controls the drivers needs via a signal from the Throttle
Position (TP) sensor on the throttle pedal.
The ECM is a full authoritative diesel specific microprocessor that also incorporates features for cruise control and air
conditioning control. In addition, the ECM supplies output control for the exhaust gas recirculation and turbocharger
boost pressure. The ECM has a self-diagnostic function, which is able to provide backup strategies for most sensor
failures.
The ECM processes information from the following input sources:
lMass air flow sensor.
lAmbient air pressure sensor.
lManifold absolute pressure/inlet air temperature sensor.
lEngine coolant temperature sensor.
lCrankshaft speed and position sensor.
lThrottle position sensor.
lFuel temperature sensor.
lAir conditioning request.
lAir conditioning fan request.
lBrake pedal switch.
lClutch switch.
lCruise control master switch.
lCruise control SET+ switch.
lCruise control RES switch.
lHigh/low ratio switch.
The input from the sensors constantly updates the ECM with the current operating condition of the engine. Once the
ECM has compared current information with stored information within its memory, it can make any adjustment it
requires to the operation of the engine via the following:
lAir conditioning clutch relay.
lAir conditioning cooling fan relay.
lElectronic vacuum regulator solenoid.
lMalfunction indicator lamp.
lFuel pump relay.
lGlow plug warning lamp.
lGlow plugs.
lFuel injectors.
lMain relay.
lTurbocharger wastegate modulator.
lTemperature gauge.
The ECM interfaces with the following:
lElectronic Automatic Transmission (EAT).
lSelf Levelling and Anti-lock Brakes System (SLABS).
lSerial communication link.
lInstrument cluster.
lBody Control Unit (BCU).

Page 402 of 1672

LAND ROVER DISCOVERY 2002 Workshop Manual ENGINE MANAGEMENT SYSTEM - TD5
DESCRIPTION AND OPERATION 18-1-9
Connector C0658
Pin No. Input/Output Function Signal type Value Interfaces
B1 Input Earth 1 0 volts 0 volts
B2 Input Earth 4 0 volts 0 v

Page 407 of 1672

LAND ROVER DISCOVERY 2002 Workshop Manual ENGINE MANAGEMENT SYSTEM - TD5
18-1-14 DESCRIPTION AND OPERATION
Engine Coolant Temperature (ECT) sensor
The ECT sensor is located in the coolant outlet elbow on the top of the engine. It provides the

Page 426 of 1672

LAND ROVER DISCOVERY 2002 Workshop Manual ENGINE MANAGEMENT SYSTEM - TD5
DESCRIPTION AND OPERATION 18-1-33
The turbocharger is exposed to extremely high operating temperatures (up to 1,000 °C (1832 °F)) because of the hot
exhaust gases and

ENGINE MANAGEMENT SYSTEM - TD5
DESCRIPTION AND OPERATION 18-1-33
The turbocharger is exposed to extremely high operating temperatures (up to 1,000 °C (1832 °F)) because of the hot
exhaust gases and the high speed revolution of the turbine (up to 150,000 rev/min). In order to resist wear of the
turbine bearings a flow of lubrication oil is supplied from the engine lubrication system to keep the bearings cool. Oil
is supplied from a tapping at the front of the full-flow filter adaptor housing via a metal pipe with banjo connections.
Oil is returned to the sump via a metal pipe which connects to the cylinder block at a port below the turbocharger
assembly.
A heatshield is attached to the left hand side of the engine to protect adjacent components from the heat generated
at the turbocharger. The heatshield is attached to the engine by two bolts an additional bolt attaches the heatshield
to the turbocharger casting.
The engine control module controls the amount of boost pressure the engine receives by way of the turbocharger.
When full boost is reached a control signal is sent to the wastegate modulator, and a vacuum is applied to the
wastegate valve. The wastegate valve opens, bypassing some of the exhaust gas away from the turbine to be output
to the exhaust system.
The engine should be allowed to idle for 15 seconds following engine start up and before the engine is switched off
to protect the turbocharger by maintaining oil supply to the turbine bearings.
Intercooler
The intercooler is an air-to-air heat exchanger which lowers the intake air temperature to obtain a higher air density
for better combustion efficiency. The intercooler receives compressed air from the turbocharger via a metal pipe; it
cools the intake air via the intercooler matrix and delivers it to the intake manifold by means of a rubber hose which
connects between the intercooler outlet and the intake manifold outlet. The rubber hose is connected to ports at each
end by metal band clips.

+ COOLING SYSTEM - Td5, DESCRIPTION AND OPERATION, Description.
The intercooler is located at the front of the engine bay, forward of the radiator.

Page 436 of 1672

LAND ROVER DISCOVERY 2002 Workshop Manual ENGINE MANAGEMENT SYSTEM - TD5
DESCRIPTION AND OPERATION 18-1-43
Air Conditioning (A/C)
The ECM controls operation of the A/C compressor and the engines electric cooling fan in response to requests f

ENGINE MANAGEMENT SYSTEM - TD5
DESCRIPTION AND OPERATION 18-1-43
Air Conditioning (A/C)
The ECM controls operation of the A/C compressor and the engine's electric cooling fan in response to requests from
the Automatic Temperature Control (ATC) ECU.
A/C request
When the ATC ECU supplies the ECM with an A/C request, the ECM energises the compressor clutch relay. The
compressor clutch relay is located in the engine compartment fuse box. It is a four pin normally open relay. This means
that the relay must be energised to drive the compressor clutch. During periods of high driver demand such as hard
acceleration or maximum rev/min the ECM will disable the compressor clutch for a short time. This is to reduce the
load on the engine.
The operation of the A/C request is via a switch being connected to earth. Voltage is supplied via pin 9 of connector
C0658 of the ECM, at the point at which the switch is pressed the connection to the earth path is made and the
compressor clutch is engaged.
The ECM provides the earth for the relay windings to allow the compressor clutch relay contacts to close and the
compressor clutch drive 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 closes down the earth path, the return spring in the relay will
pull the contacts apart to shut down the compressor clutch drive. Fuse 6, located in the engine compartment fuse box,
provides voltage to the compressor clutch relay switching contacts. The relay windings are supplied with battery
voltage from the main relay, also located in the engine compartment fuse box. The earth path for the relay windings
is via pin 29 of the ECM connector C0658. When the relay is energised the output from the switching contacts is
directly to the compressor clutch.
Cooling fan request
The A/C fan request is an input to the ECM from the ATC ECU to request that the engine's electric cooling fan is
activated to provide additional cooling for the A/C condenser.
The cooling fan relay is located in the engine compartment fuse box and is also controlled by the ECM. It is a four pin
normally open relay. This means that the relay must be energised to drive the cooling fan. The cooling 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 sensor fails.
The operation of the cooling fan request is via a switch being connected to earth. Voltage is supplied via pin 23 of
connector C0658 of the ECM, at the point at when the switch is pressed the connection to the earth path is made and
the cooling fan is engaged.
The ECM provides the earth for the cooling fan relay windings 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 closes down 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 A/C cooling fan relay switching contacts is via fuse 4
located in the engine compartment fuse box. The relay windings are supplied with battery voltage from the main relay,
also located in the engine compartment fuse box. The earth path for the relay windings is via pin 4 of the ECM
connector C0658. When the relay is energised the output from the switching contacts is directly to the cooling fan
motor.

Page 440 of 1672

LAND ROVER DISCOVERY 2002 Workshop Manual ENGINE MANAGEMENT SYSTEM - TD5
REPAIRS 18-1-47
REPAIRS
Engine control module (ECM)
$% 18.30.03
All replacement ECMs are configured for two track
TP sensors. When fitting replacement ECM to
vehicl

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