2002 LAND ROVER DISCOVERY battery

ENGINE MANAGEMENT SYSTEM - TD5
DESCRIPTION AND OPERATION 18-1-29
Malfunction Indicator Lamp (MIL)
The MIL is located in the instrument cluster. It illuminates to alert the driver to system malfunctions. During ignition a
self-test function of the lamp is carried out. The lamp will illuminate for 3 seconds then extinguish if no faults exist. If
a fault is present the lamp will be extinguished for 1 second before illuminating.
Input/Output
The MIL is supplied with battery voltage from the instrument cluster. When the ECM detects a fault, it provides an
earth path to illuminate the MIL. The earth path is via pin 6 of ECM connector C0658.

ENGINE MANAGEMENT SYSTEM - TD5
18-1-30 DESCRIPTION AND OPERATION
Glow plug warning lamp
The glow plug warning lamp is located in the instrument cluster. It illuminates to alert the driver that the glow plugs
are being heated prior to the engine being started. The length of time that the lamp illuminates and the glow plugs
are operating prior to cranking is the pre-heat period, which is subject to battery voltage and ECT sensor signal
controlled by the ECM.
Input/Output
The instrument cluster supplies battery voltage to the glow plug warning lamp. The ECM provides an earth path to
illuminate the lamp. The earth path is via pin 30 of ECM connector C0658.
Glow plugs
The 4 glow plugs are located in the engine block on the inlet side, in cylinder 1 to 4. Cylinder 5 has no glow plug. The
glow plugs are a vital part of the engine starting strategy.

ENGINE MANAGEMENT SYSTEM - TD5
DESCRIPTION AND OPERATION 18-1-31
The purpose of the glow plugs is:
lAssist cold engine start.
lReduce exhaust emissions at low engine load/speed.
The main part of the glow plug is a tubular heating element that protrudes into the combustion chamber of the engine.
The heating element contains a spiral filament that is encased in magnesium oxide powder. At the tip of the tubular
heating element is the heater coil. Behind the heater coil and connected in series is a control coil. The control coil
regulates the heater coil to ensure that it does not overheat and cause a possible failure. The glow plug circuit has its
own control relay located in the engine compartment fuse box.
Pre-heat is the length of time the glow plugs operate prior to engine cranking. The ECM controls the pre-heat time of
the glow plugs based on battery voltage and coolant temperature information via the glow plug relay.
Post-heat is the length of time the glow plugs operate after the engine starts. The ECM controls the post-heat time
based on ECT information. If the ECT fails the ECM will operate pre/post-heat time strategies with default values from
its memory. The engine will be difficult to start.
Input/Output
The glow plugs receive voltage from the glow plug relay that is controlled by the ECM. The ECM provides the earth
path for the relay coil closing the relay contacts and supplying the glow plugs with battery voltage. The supply voltage
heats the coils to approximately 1000
°C (1832 °F). The glow plug circuit is wired in parallel, the body of each glow
plug is screwed directly into the engine block which provides each glow plug with an earth path.
The glow plugs can fail in the following ways:
lHeater coil open circuit.
lControl coil open circuit.
lPoor earth quality.
lShort circuit to vehicle supply.
lShort circuit to vehicle earth.
lWiring loom fault.
lRelay windings open circuit.
lIncorrect relay fitted.
In the event of a glow plug failure any of the following symptoms may be observed:
lDifficult starting.
lExcessive smoke emissions after engine start.

ENGINE MANAGEMENT SYSTEM - TD5
18-1-34 DESCRIPTION AND OPERATION
Turbocharger wastegate modulator
The turbocharger wastegate modulator is located on the ancillary bracket on the engine, and is connected by flexible
pipes to the turbocharger. The modulator controls turbocharger boost pressure by varying the pressure used to open
the turbocharger wastegate. This control is vital to ensure the turbocharger does not over boost the engine.
Input/Output
The turbocharger wastegate modulator receives battery voltage from the main relay. The ECM supplies the earth path
in the form of a pulse width modulated (PWM) signal. The PWM signal from the ECM operates the modulator at a
frequency of less than 50 Hz. This signal allows the turbocharger wastegate modulator to open and close the
wastegate. This permits a proportion of the exhaust gas to bypass the turbocharger through the wastegate, thereby
regulating boost pressure.
Input voltage to the turbocharger wastegate modulator is via the main relay.
The earth path is via a PWM signal generated at pin 21 of the ECM connector C0158.
The turbocharger wastegate modulator can fail as follows:
lOpen circuit.
lShort circuit to voltage supply.
lShort circuit to vehicle earth.
lWiring loom fault.
lConnector water ingress.
lConnector failure due to excess heat.
lComponent failure due to excess heat.
lComponent failure due to excess vibration.
In the event of a turbocharger wastegate modulator failure any of the following symptoms may be observed:
lReduced engine performance.
lIncreased engine performance.
lLack of power.
lExcess smoke.
lReduced fuel economy.
The MIL will not illuminate in the event of a turbocharger wastegate modulator failure.

ENGINE MANAGEMENT SYSTEM - TD5
DESCRIPTION AND OPERATION 18-1-39
With the ECM in a 'Secure' state, it will not function unless an alarm system is fitted to the vehicle. A 'Secure' ECM
cannot be configured into a 'No Code' ECM.
With the ECM in a 'No Code' state, it does not require an alarm system to be fitted to allow the engine to operate. If
the ECM senses that an alarm system is fitted it will not start. A 'No Code' ECM can be configured to a 'Secure' ECM
using TestBook. A 'Secure' ECM can not be configured to a 'No Code' state.
Setting up of the ECM immobilisation configurations can only be performed using TestBook.
If a vehicle stalls immediately after starting it is possible that it has been immobilised. This means either:
lThe ECM was configured as 'No Code' but the ECM is receiving a code at its alarm input pin.
lThe ECM received an incorrect code.
lThe ECM was expecting a security code but did not receive one at its alarm input pin.
Fuel delivery/injection control
The fuel delivery/injection control delivers a precise amount of finely atomised fuel to mix with the air in the
combustion chamber to create a controlled explosion.
To precisely control fuel delivery and control fuel injection, the following input conditions must be met:
lCKP information.
lInjection timing map information.
lFT information.
lECT information.
The ECM monitors the conditions required for optimum combustion of fuel in the cylinder from the various sensors
around the engine and then compares it against stored information. From this calculation the ECM can adjust the
quantity and timing of the fuel being delivered to the cylinder.
The ECM uses CKP information as follows:
lTo calculate engine speed.
lTo determine engine crankshaft position.
Engine speed and crankshaft position allows the ECM to determine fuel injection timing.
The ECM also uses ECT information and FT sensor information to allow optimum fuel delivery and injection control
for all engine coolant and fuel temperatures.
Turbocharger control
Turbocharger control is vital to ensure the turbocharger does not over boost the engine. Within the turbocharger is a
wastegate, which when operated by the turbocharger wastegate modulator will open and close a bypass valve
regulating boost pressure.
The turbocharger wastegate modulator, via the ECM, controls boost pressure under the following conditions:
lAcceleration.
lWide open throttle.
lIdle.
lOverrun.
The turbocharger wastegate modulator receives a battery voltage supply from the main relay. The ECM supplies the
earth path in the form of a pulse width modulation (PWM) signal. This signal allows the turbocharger wastegate
modulator to open and close the wastegate. A proportion of the exhaust gas can bypass the turbocharger through
the wastegate, regulating boost pressure.

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.

ENGINE MANAGEMENT SYSTEM - TD5
ADJUSTMENTS 18-1-45
ADJUST ME NTS
Glow plug
$% 19.90.20.01
Check
1.Remove glow plug.

+ ENGINE MANAGEMENT SYSTEM -
Td5, REPAIRS, Glow plugs.
2.Using tool LRT-12-511connect RED lead to
battery '+' positive and the BLACK lead to
battery '-' negative.
3.Position glow plug into tester and retain with
spring loaded bar.
4.Connect YELLOW lead to glow plug terminal.
5.Press red button on tester and note ammeter
reading. Keep button depressed, glow plug tip
should start to glow after 5 seconds.The tip of
the plug must glow first, if it fails to do so,
replace glow plug.
6.The ammeter reading should show an initial
current draw of 25 amps, which should fall to
12 amps after 20 seconds.
7.Refit glow plug.

+ ENGINE MANAGEMENT SYSTEM -
Td5, REPAIRS, Glow plugs.

ENGINE MANAGEMENT SYSTEM - TD5
REPAIRS 18-1-47
REPAIRS
Engine control module (ECM)
$% 18.30.03
All replacement ECM's are configured for two track
TP sensors. When fitting replacement ECM to
vehicle with three track TP sensor, TestBook must be
used to configure ECM for three track TP sensor.
Remove
1.Release fixings and remove battery cover.
2.Disconnect battery earth lead.
3.Release retaining strap and remove vehicle
jack.
4.Remove screw, release ECM and disconnect 2
multiplugs.
5.Remove ECM.
Refit
1.Position new ECM and connect multiplugs.
2.Fit ECM and tighten screw.
3.Fit vehicle jack and secure retaining strap.
4.Connect battery earth lead.
5.Fit battery cover and secure with fixings.
6.Programme ECM using TestBook.
Sensor - engine coolant temperature
(ECT)
$% 18.30.10
Remove
1.Remove fixings and remove engine acoustic
cover.
2.Release fixings and remove cooling fan cowl.
3.Disconnect multiplug from ECT sensor.
4.Remove sensor from coolant outlet elbow and
discard sealing washer.
Refit
1.Clean ECT sensor and coolant outlet elbow
mating faces.
2.Fit new sealing washer to ECT sensor. Fit
sensor and tighten to 15 Nm (11 lbf.ft). Connect
multiplug.
3.Fit cooling fan cowl and secure with fixings.
4.Fit engine acoustic cover and secure with
fixings.
5.Top up cooling system.

+ MAINTENANCE, PROCEDURES,
Cooling system.