1999 LAND ROVER DEFENDER brake

EMISSION CONTROL
5
DESCRIPTION AND OPERATION
CAUTION: Inset A shows the Pre-EU3 condition for the EGR pipe. Inset B shows the Pre-EU3
condition filter and venting.
1.ILT valve modulator
2.ILT modulator vacuum hose (brown)
3.EGR valve modulator
4.EGR modulator vacuum hose (brown)
5.Vent hose - EGR modulator to in-line filter (green)
6.Vacuum hose to ILT valve suction port (blue)
7.Vacuum hose to EGR valve suction port (blue)
8.’T’-piece (4-way)
9.Vacuum hose to brake servo
10.Non-return valve
11.Brake servo
12.Inlet manifold
13.Exhaust manifold
14.ILT valve
15.EGR cooler - EU-3 models
16.Vacuum pump/alternator assembly
17.Air intake hose from intercooler
18.EGR valve (incorporating ILT valve) assembly
19.Vacuum hose to vacuum pump
20.Vent hose - ILT valve modulator to in-line filter (green)
21.3-way connector
22.Vent hose to air cleaner
23.ILT modulator harness connector (green)
24.EGR modulator harness connector (black)
25.To atmosphere - Pre-EU3 models
26.In-line filter - Pre-EU3 models
27.EGR pipe - Pre-EU3 models
ProCarManuals.com

EMISSION CONTROL
9
DESCRIPTION AND OPERATION EGR MODULATOR
1.Port to vacuum source (white band)
2.Port to EGR valve (blue band)3.Port to atmosphere via in-line filter (green band)
4.Harness connector
The EGR modulator is located on a plate fixed to the inner RH front wing. The modulator is attached to the plate
by two studs, each with two nuts which secure the assembly to a rubber mounting, which helps reduce noise. The
modulator must be mounted vertically with the two vacuum ports uppermost.
Modulator operation is controlled by a signal from the ECM which determines the required amount of EGR needed
in response to inputs relating to air flow, engine operation, and ambient conditions. The modulator has a two pin
connector at its base to connect it to the ECM via the engine harness.
The modulator features three ports:
The top port is identified by a white band and connects to a T-piece in the vacuum line via a small bore light
brown plastic hose. The two other ports on the T-piece connect to the vacuum line hoses of black vinyl tubing
between the vacuum pump and the brake servo assembly attached to the bulkhead. The vacuum pump end of
the tubing terminates in a rubber elbow, which gives a vacuum tight seal on the suction port of the vacuum
pump. The brake servo end of the tubing terminates with a non-return valve in a plastic housing which plugs
into the front face of the brake servo housing.
The middle port is identified by a blue band, and connects to the suction port on the EGR valve through a small
bore blue plastic hose.
The lower port is identified by a green band and connects to atmosphere through an in-line filter via a small
bore green plastic hose.
The blue and brown vacuum hoses are protected by corrugated plastic sheaths. The ends of the hoses are fitted
with rubber boots to ensure vacuum tight seals at the component ports.
ProCarManuals.com

17EMISSION CONTROL
10
DESCRIPTION AND OPERATION INLET THROTTLE (ILT) MODULATOR
1.Port to vacuum source (white band)
2.Port to ILT valve (blue band)
3.Port to atmosphere via in-line filter (green band)
4.Harness connector (green)
The ILT modulator is located on a plate fixed to the inner wing on the RH side of the engine below the EGR
modulator. The modulator is attached to the plate by two through-studs, each with two nuts which secure the
modulator assembly to a rubber mounting which helps to reduce noise. The modulator must be mounted in the
vertical orientation with the two vacuum ports uppermost.
The modulator operation is controlled by a signal from the ECM which determines the required ratio of exhaust
gas to fresh inlet air needed in response to inputs relating to air flow and engine operating and ambient conditions.
The modulator has a green two-pin connector at its base to connect it to the ECM through the engine harness.
The ILT valve modulator features three ports:
The top port is identified by a white band and connects to a’T’-piece in the vacuum line via a small-bore brown
plastic hose where it is connected in parallel with the vacuum source line to the EGR valve modulator. The two
other ports on the’T’-piece connect vacuum line hoses of black vinyl tubing between the vacuum pump
attached to the alternator and the brake-servo assembly attached to the bulkhead.
The middle port is identified by a blue band and connects to the suction port on the ILT valve through a
small-bore blue plastic hose.
The lower port is identified by a green band and connects to atmosphere through an in-line filter via a green
plastic hose and a three-way connector positioned in-line between the modulators and the filter. The ILT
modulator hose is connected opposite to the two parallel ports at the three-way connector which connect the
vent lines to the EGR valve modulator and the in-line filter. The other port of the in-line filter vents directly to
atmosphere.
The blue and brown vacuum hoses are protected by corrugated plastic sheaths. The ends of the hoses are fitted
with rubber boots to ensure vacuum tight seals at the component ports.
ProCarManuals.com

18 - ENGINE MANAGEMENT SYSTEM
CONTENTS
Page
DESCRIPTION AND OPERATION
COMPONENT LOCATION 2...................................................................................
DESCRIPTION 5.....................................................................................................
ENGINE CONTROL MODULE (ECM) 6.................................................................
SENSOR - MASS AIR FLOW (MAF) 7....................................................................
SENSOR - AMBIENT AIR PRESSURE AND 8.......................................................
SENSOR - MANIFOLD ABSOLUTE PRESSURE 9................................................
SENSOR - ENGINE COOLANT TEMPERATURE 11.............................................
SENSOR - CRANKSHAFT SPEED AND 12...........................................................
SENSOR - THROTTLE POSITION (TP) 14............................................................
SENSOR - THROTTLE POSITION (TP) 15............................................................
ELECTRONIC UNIT INJECTOR (EUI) 18...............................................................
SENSOR - FUEL TEMPERATURE (FT) 20............................................................
RELAY - FUEL PUMP 21........................................................................................
RELAY - MAIN 21...................................................................................................
SWITCH - BRAKE PEDAL 22.................................................................................
SWITCH - CLUTCH PEDAL 22...............................................................................
MODULATOR - EXHAUST GAS REGULATOR (EGR) 23.....................................
WARNING LAMP - GLOW PLUG 23......................................................................
GLOW PLUGS 24...................................................................................................
TURBOCHARGER 26.............................................................................................
INTERCOOLER 27.................................................................................................
OPERATION 28......................................................................................................
REPAIR
ENGINE CONTROL MODULE (ECM) 1.................................................................
SENSOR - ENGINE COOLANT TEMPERATURE (ECT) 1....................................
SENSOR - CRANKSHAFT SPEED AND POSITION (CKP) 2................................
ProCarManuals.com

18ENGINE MANAGEMENT SYSTEM
4
DESCRIPTION AND OPERATION Passenger Compartment
1.Brake pedal switch.
2.Clutch pedal switch.
3.Accelerator pedal switch.
4.Diagnostic connector.
ProCarManuals.com

ENGINE MANAGEMENT SYSTEM
5
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 principal. 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 air conditioning. In
addition, the ECM supplies output control for the Exhaust Gas Recirculation (EGR) 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:
Mass Air Flow (MAF) sensor.
Ambient Air Pressure (AAP) sensor.
Manifold Absolute Pressure (MAP) / Inlet Air Temperature (IAT) sensor.
Engine Coolant Temperature (ECT) sensor.
Crankshaft Speed and Position (CKP) sensor.
Throttle Position (TP) sensor.
Fuel Temperature (FT) sensor.
Air conditioning request.
Air conditioning fan request.
Brake pedal switch.
Clutch pedal 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:
Air conditioning clutch relay.
Air conditioning cooling fan relay.
Electronic vacuum regulator solenoid.
Fuel pump relay.
Glow plug warning lamp.
Glow plugs.
Fuel injectors.
Main relay.
Turbocharger wastegate modulator.
Temperature gauge.
The ECM interfaces with the following:
Serial communication link.
Instrument pack.
ProCarManuals.com

18ENGINE MANAGEMENT SYSTEM
22
DESCRIPTION AND OPERATION SWITCH - BRAKE PEDAL
The brake pedal switch is located at the rear of the brake pedal box, and activates when the brake pedal is
operated. The ECM uses the signal from the brake pedal to activate the brake lamps and to limit fuelling under
braking.
The brake pedal switch can fail in any of the following ways:
Switch open circuit.
Short circuit to vehicle supply.
Short circuit to earth.
SWITCH - CLUTCH PEDAL
The clutch pedal switch is located on the clutch master cylinder and is activated when the clutch pedal is operated.
The ECM uses the signal from the clutch pedal switch to provide surge damping during gear change. Surge
damping stops engine speed rising dramatically (engine flaring) during gear change. Surge damping assists
driveability as follows:
Smoother gear change.
Greater exhaust gas emission control.
Improved fuel consumption.
Input / Output
When the clutch pedal is in the rest position, the clutch switch is closed. This allows a feed to flow from the switch
(C0667-1) to the ECM (C0658-35) on a black/white wire. When the clutch pedal is pressed the switch contacts
open, cutting the feed to the ECM.
The clutch pedal switch can fail in any one of the following ways:
Switch open circuit.
Short circuit to vehicle supply.
Short circuit to vehicle earth.
In the event of a clutch pedal switch failure surge damping will be inactive.
ProCarManuals.com

CLUTCH
3
DESCRIPTION AND OPERATION 1.Brake/clutch reservoir
2.Connecting hose
3.Bolt - 2 off
4.Master cylinder
5.Clutch pedal
6.Gearbox housing
7.Primary driveshaft
8.Bolt - 2 off
9.Slave cylinder
10.Bleed nipple
11.Pressure plate
12.Drive plate
13.Dual mass flywheel
14.Metal hydraulic pipe
15.Ball spigot
16.Clutch release bearing sleeve
17.Bolt - 2 off
18.Pivot washer
19.Release lever
20.Release bearing
21.Retaining clip
22.Bolt
23.Plastic hydraulic pipe
ProCarManuals.com