fuel type LAND ROVER DISCOVERY 1999 Owner's Manual

EMISSION CONTROL - V8
DESCRIPTION AND OPERATION 17-2-41
EVAP System, Leak Detection Diagnostic (vacuum type)
The EVAP system leak detection is performed as follows:
1The ECM checks that the signal from the fuel tank pressure sensor is within the expected range. If the signal is
not within range, the leakage test will be cancelled.
2Next the purge valve is held closed and the canister vent solenoid (CVS) valve is opened to atmosphere. If the
ECM detects a rise in pressure with the valves in this condition, it indicates there is a blockage in the fuel
evaporation line between the CVS valve and the EVAP canister, or that the CVS valve is stuck in the closed
position and thus preventing normalisation of pressure in the fuel evaporation system. In this instance, the
leakage test will be cancelled.
3The CVS valve and the purge valve are both held in the closed position while the ECM checks the fuel tank
pressure sensor. If the fuel tank pressure sensor detects a decline in pressure, it indicates that the purge valve
is not closing properly and vapour is leaking past the valve seat face under the influence of the intake manifold
depression. In this instance, the leakage test will be cancelled.
4If the preliminary checks are satisfactory, a compensation measurement is determined next. Variations in fuel
level occur within the fuel tank, which will influence the pressure signal detected by the fuel tank pressure
sensor. The pressure detected will also be influenced by the rate of change in the fuel tank pressure, caused by
the rate of fuel evaporation which itself is dependent on the ambient temperature conditions. Because of these
variations, it is necessary for the ECM to evaluate the conditions prevailing at a particular instance when testing,
to ensure that the corresponding compensation factor is included in its calculations.
The CVS valve and purge valves are both closed while the ECM checks the signal from the fuel tank pressure
sensor. The rise in fuel pressure detected over a defined period is used to determine the rate of fuel evaporation
and the consequent compensation factor necessary.
5With the CVS valve still closed, the purge valve is opened. The inlet manifold depression present while the purge
valve is open, decreases EVAP system pressure and sets up a small vacuum in the fuel tank. The fuel tank
pressure sensor is monitored by the ECM and if the vacuum gradient does not increase as expected, a large
system leak is assumed by the ECM (e.g. missing or leaking fuel filler cap) and the diagnostic test is terminated.
If the EVAP canister is heavily loaded with hydrocarbons, purging may cause the air:fuel mixture to become
excessively rich, resulting in the upstream oxygen sensors requesting a leaner mix from the ECM to bring the
mixture back to the stoichiometric ideal. This may cause instability in the engine idle speed and consequently
the diagnostic test will have to be abandoned. The ECM checks the status of the upstream oxygen sensors
during the remainder of the diagnostic, to ensure the air:fuel mixture does not adversely affect the engine idle
speed.
6When the fuel tank pressure sensor detects that the required vacuum has been reached (-800 Pa), the purge
valve is closed and the EVAP system is sealed. The ECM then checks the change in the fuel tank pressure
sensor signal (diminishing vacuum) over a period of time, and if it is greater than expected (after taking into
consideration the compensation factor due to fuel evaporation within the tank, determined earlier in the
diagnostic), a leak in the EVAP system is assumed. If the condition remains, the MIL warning light will be turned
on after two drive cycles.
The decrease in vacuum pressure over the defined period must be large enough to correspond to a hole
equivalent to 1 mm (0.04 in.) diameter or greater, to be considered significant enough to warrant the activation
of an emissions system failure warning.
The diagnostic test is repeated at regular intervals during the drive cycle, when the engine is at idle condition. The
diagnostic test will not be able to be performed under the following conditions:
lDuring EVAP canister purging
lDuring fuelling adaption
lIf excess slosh in the fuel tank is detected (excess fuel vapour will be generated, invalidating the result)
Following the test, the system returns to normal purge operation after the canister vent solenoid opens. Possible
reasons for an EVAP system leak test failure are listed below:
lFuel filler not tightened or cap missing.
lSensor or actuator open circuit.
lShort circuit to vehicle supply or ground.
lEither purge or CVS valve stuck open.
lEither purge or CVS valve stuck shut or blocked pipe.
lPiping broken or not connected.
lLoose or leaking connection.

EMISSION CONTROL - V8
17-2-42 DESCRIPTION AND OPERATION
If the piping is broken forward of the purge valve or is not connected, the engine may run rough and fuelling adaptions
will drift. The fault will not be detected by the leak detection diagnostic, but it will be determined by the engine
management ECM through the fuelling adaption diagnostics.
The evaluation of leakage is dependent on the differential pressure between the fuel tank and ambient atmospheric
pressure, the diagnostic is disabled above altitudes of 9500 ft. (2800 m) to avoid false detection of fuel leaks due to
the change in atmospheric pressure at altitude.
Fuel Leak Detection System Operation (positive pressure leak detection type) – NAS only
The EVAP system with positive pressure leak detection capability used on NAS vehicles is similar to the standard
system, but also includes a fuel evaporation leak detection pump with integral solenoid valve. It is capable of detecting
holes in the EVAP system down to 0.5 mm (0.02 in.). The test is carried out at the end of a drive cycle, when the
vehicle is stationary and the ignition switch has been turned off. The ECM maintains an earth supply to the Main relay
to hold it on, so that power can be supplied to the leak detection pump.
First a reference measurement is established by passing the pressurised air through a by-pass circuit containing a
fixed sized restriction. The restriction assimilates a 0.5 mm (0.02 in) hole and the current drawn by the pump motor
during this procedure is recorded for comparison against the value to be obtained in the system test. The purge valve
is held closed, and the reversing valve in the leak detection pump module is not energised while the leak detection
pump is switched on. The pressurised air from the leak detection pump is forced through an orifice while the current
drawn by the pump motor is monitored.
Next the EVAP system diagnostic is performed; the solenoid valve is energised so that it closes off the EVAP system's
vent line to atmosphere, and opens a path for the pressurised air from the leak detection pump to be applied to the
closed EVAP system.
The current drawn by the leak detection pump is monitored and checked against that obtained during the reference
measurement. If the current is less than the reference value, this infers there is a hole in the EVAP system greater
than 0.5 mm (0.02 in) which is allowing the positive air pressure to leak out. If the current drawn by the pump motor
is greater than the value obtained during the reference check, the system is sealed and free from leaks. If an EVAP
system leak is detected, the ECM stores the fault in diagnostic memory and the MIL light on the instrument pack is
illuminated.
On NAS vehicles, the ECM works on a 2 trip cycle before illuminating the MIL. On EU-3 vehicles, the ECM works on
a 3 trip cycle before illuminating the MIL.
Following the test, the solenoid valve is opened to normalise the EVAP system pressure and the system returns to
normal purge operation at the start of the next drive cycle. Possible reasons for an EVAP system leak test failure are
listed below:
lFuel filler not tightened or cap missing.
lSensor or actuator open circuit.
lShort circuit to vehicle supply or ground.
lEither purge or solenoid valve stuck open.
lEither purge or solenoid valve stuck shut.
lBlocked pipe or air filter.
lPiping broken or not connected.
lLoose or leaking connection.
If the piping is broken forward of the purge valve or is not connected, the engine may run rough and fuelling adaptions
will drift. The fault will not be detected by the leak detection test, but will be determined by the engine management
ECM through the fuelling adaption diagnostics. This test can be run from TestBook/T4.

ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-9
Pin out details connector C0634
Connector 2 (C0635): This connector contains 24 pins and is primarily used for Heated Oxygen Sensors (HO
2S)
control and earth. The HO
2S sensors require a heater circuit to assist in heating the tip of the sensors to enable closed
loop fuelling to be implemented quickly after cold starting.
Pin out details connector C0635
Pin No. Function Signal type Reading
1 Ignition position II Input 12 V
2 Not used - -
3 Not used - -
4 Chassis earth Earth 0V
5 Fuel injectors earth Earth 0V
6 Power stage earth Earth 0V
7 Permanent battery supply Input battery supply 12V
8 Switched relay positive Input switched 0-12V
9 Not used - -
Pin No. Function Signal type Reading
1HO
2S heater RH bank - downstream Output PWM 12-0V
2 Not used - -
3 Not used - -
4 Not used - -
5 Thermostat monitoring sensor Earth 0V
6 Not used - -
7HO
2S heater LH bank - downstream Output PWM 12-0V
8HO
2S sensor RH bank - downstream Earth/ Signal 0V
9HO
2S sensor LH bank - upstream Earth/ Signal 0V
10 HO
2S sensor RH bank - upstream Earth/ Signal 0V
11 HO
2S sensor LH bank - downstream Earth/ Signal 0V
12 Not used - -
13 HO
2S heater RH bank - upstream Output PWM 12-0V
14 HO
2S sensor RH bank - downstream Input/ Signal Analogue 0-5V
15 HO
2S sensor LH bank - upstream Input/ Signal Analogue 0-5V
16 HO
2S sensor RH bank - upstream Input/ Signal Analogue 0-5V
17 HO
2S sensor LH bank - downstream Input/ Signal Analogue 0-5V
18 Fuel pump relay Output Switch to earth
19 HO
2S heater LH bank - upstream Output PWM 12-0V
20 Not used - -
21 Thermostat monitoring sensor Signal Analogue 0-5V
22 Not used - -
23 Main relay Output Switch to earth
24 EVAP system leak detection pump motor (NAS
vehicles with positive pressure type, EVAP system
leak detection capability only)Output Switch to earth

ENGINE MANAGEMENT SYSTEM - V8
18-2-10 DESCRIPTION AND OPERATION
Connector 3 (C0636): This connector contains 52 pins and is used for most sensor and actuator inputs and outputs.
Sensor and actuator control is vital to ensure that the ECM maintains adaptive strategy
Pin out details connector C0636
Pin No. Function Signal type Reading
1 Injector cylinder number 2 Output Switch to earth
2 Injector cylinder number 5 Output Switch to earth
3 Purge valve Output, signal PWM 12-0V
4 SAI vacuum solenoid valve (NAS vehicles from 2000MY
only)Output Switch to earth
5 Not used - -
6 Fuel tank pressure sensor (NAS vehicles with vacuum type,
EVAP system leak detection only)Earth 0V
7 MAF sensor 5V supply Output, reference 5V
8 Not used - -
9 MAF sensor earth Earth 0V
10 TP sensor 5V supply Output, reference 5V
11 Not used - -
12 Not used - -
13 Not used - -
14 Injector cylinder number 7 Output Switch to earth
15 Injector cylinder number 6 Output Switch to earth
16 SAI pump relay (NAS vehicles from 2000MY only) Output Switch to earth
17 CMP sensor Earth 0V
18 Low range switch (manual transmission only) Input, signal Active low
19 Not used - -
20 CMP signal Input, signal Digital switch 0-12V
21 ECT sensor Earth 0V
22 Coolant temperature signal Input, signal Analogue 0-5V
23 MAF sensor signal Input, signal Analogue 0-5V
24 TP sensor signal Input, signal Analogue 0-5V
25 TP sensor earth Earth 0V
26 Not used - -
27 Injector cylinder number 3 Output Switch to earth
28 Injector cylinder number 8 Output Switch to earth
29 Hill decent control output Output, signal PWM 0-12V
30 EVAP canister vent solenoid (CVS) valve (NAS vehicles with
vacuum type, EVAP system leak detection only)Output Switch to earth
30 Leak detection pump solenoid (NAS vehicles with positive
pressure type, EVAP system leak detection only)Output Switch to earth
31 A/C condenser fan Output Switch to earth
32 CKP sensor signal Input, signal Analogue, 0-300V peak
33 Not used - -
34 IAT sensor signal Input, signal Analogue 0-5V
35 KS, RH bank earth Earth 0V
36 KS, RH bank signal Input, signal Analogue
37 Not used - -
38 Not used - -
39 Not used - -
40 Injector cylinder number 4 Output Switch to earth
41 Injector cylinder number 1 Output Switch to earth
42 Idle air control valve open Output, signal PWM 12-0V
43 Idle air control valve close Output, signal PWM 12-0V
44 ECT sensor signal Output, signal PWM 0-12V

ENGINE MANAGEMENT SYSTEM - V8
18-2-12 DESCRIPTION AND OPERATION
Connector 4 (C0637): This connector contains 40 pins and facilitates use of TestBook via the Diagnostic connector.
Also contained in this connector is the Malfunction Indicator Lamp (MIL), this instrument panel lamp informs the driver
of concerns within the engine management system.
Pin out details connector C0637
Pin No. Function Signal type Reading
1 Not used - -
2 Not used - -
3 Not used - -
4 Not used - -
5 Not used - -
6 Not used - -
7 Not used - -
8 Low fuel level Input, signal Active high
9 Fuel tank pressure sensor (NAS vehicles with
vacuum type, EVAP system leak detection
capability only)Output, reference 5V
10 Not used - -
11 Not used - -
12 Analogue fuel level (NAS vehicles with positive
pressure type, EVAP system leak detection only)Input, signal 0-5V
13 Not used - -
14 Fuel tank pressure sensor (NAS vehicles with
vacuum type, EVAP system leak detection
capability only)Input, signal Analogue 0-5V
15 Not used - -
16 ATC compressor request Input, signal Active low
17 Engine speed output Output, signal PWM 0-5V
18 Not used - -
19 Not used - -
20 Malfunction indicator lamp 'ON' Output Switched earth
21 Not used - -
22 Vehicle speed signal (VSS) Input, signal PWM 0-12V
23 Not used - -
24 Not used - -
25 Not used - -
26 Not used - -
27 Not used - -
28 Not used - -
29 ATC compressor relay Output Switched earth
30 Not used - -
31 Positive pressure type EVAP system heater (02MY
vehicles only)Output, drive Switched earth
32 Diagnostic connector K-line Bi-directional Serial 0-12V
33 Immobiliser serial W link Input, signal Serial 0-12V
34 Rough road signal Input, signal PWM 0-12V
35 Not used - -
36 CAN data bus 'high line' Bi-directional 5-2.5V
37 CAN data bus 'low line' Bi-directional 0-2.5V
38 ATC stand by Input, signal Active low
39 Not used - -
40 Not used - -

ENGINE MANAGEMENT SYSTEM - V8
18-2-22 DESCRIPTION AND OPERATION
Input/Output
The ECM provides the thermostat monitoring sensor with a 5 volt reference via pin 21 of connector C0635 of the ECM,
and an earth via pin 5 of connector C0635 of the ECM.
There are three types of thermostat monitoring sensor diagnostic checks:
lSensor signal is above maximum threshold. For the ECM to register this as a fault, and illuminate the MIL, the
temperature registered by the thermostat monitoring sensor must be above 140 °C (284 °F) for more than 1
second.
lSensor signal is below minimum threshold. For the ECM to register this as a fault, and illuminate the MIL, the
temperature registered by the thermostat monitoring sensor must be below -33 °C (-27 °F) for more than 1
second, while the inlet air temperature reading is greater than -32 °C (-25 °F).
lSignal difference between ECT sensor and thermostat monitoring sensor is below maximum threshold. For the
ECM to register this as a fault, and illuminate the MIL, the following conditions must exist:
lNo maximum or minimum threshold signal faults exist.
lNo faults are recorded against the thermostat monitoring sensor or vehicle speed signal.
lEngine not in idle speed control.
lFuel cut-off not active.
lEngine speed is greater than 400 rpm.
lRoad speed is greater than 0 mph.
lIntegrated mass air flow from engine start to fuel cut-off is greater than set value (between 3 kg and 10 kg
dependent upon engine coolant temperature at engine start).
lEngine coolant temperature at engine start is between 9 °C and 39 °C (48 °F and 102 °F).
lHigh range is selected.
lDelay time before thermostat monitoring is enabled is between set limits (between 50 and 500 seconds
dependent upon engine coolant temperature at engine start).
lEngine coolant temperature is greater than 90 °C (194 °F).
lThe difference between the ECT sensor reading and the thermostat monitoring sensor reading is less than
39 °C (102 °F).

ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-27
There are two types of IAT sensor diagnostic checks:
lThe IAT sensor signal is less than the minimum threshold – the engine has to have been running for longer than
180 seconds, and idle speed control must have been operational for longer than 10 seconds. No fuel cut off is
active. The IAT sensor signal must be less than -35°C (-31°F) for longer than 200 ms.
lThe IAT sensor signal is greater than the maximum threshold – the ECM has to be powered up (engine does not
need to be running), and the signal must be greater than 140°C (284°F) for longer than 200 ms.
If the IAT sensor fails the following fault codes will be produced and can be retrieved by TestBook:
Air intake duct – Gulf models from 2000MY
1Heat reflective insulation2Supplementary 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.
P code J2012 description Land Rover description
P0112 Intake air temperature circuit low input Intake air temperature signal less than minimum
threshold, after time for exhaust to warm up
P0113 Intake air temperature circuit high input Intake air temperature signal greater than maximum
threshold
M180452
1
2

ENGINE MANAGEMENT SYSTEM - V8
18-2-34 DESCRIPTION AND OPERATION
In the event of fuel injector signal failure any of the following symptoms may be observed:
lRough running.
lDifficult starting.
lEngine misfire.
lPossible catalyst damage.
lHigh emissions.
lAdaptive fuelling disabled.
lAdaptive idle speed control disabled.
The ECM performs three types of fuel injector diagnostic check:
lOutput short circuit to earth
lOutput short circuit to battery voltage
lOutput open circuit
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
P0201 Injection circuit malfunction - cylinder 1 Injector 1 open circuit
P0261 Cylinder 1 injector circuit low Injector 1 short circuit to earth
P0262 Cylinder 1 injector circuit high Injector 1 short circuit to battery supply
P0301 Cylinder 1 misfire detected Injector 1 excess emissions/catalyst damaging level of
misfire
P0202 Injection circuit malfunction - cylinder 2 Injector 2 open circuit
P0264 Cylinder 2 injector circuit low Injector 2 short circuit to earth
P0265 Cylinder 2 injector circuit high Injector 2 short circuit to battery supply
P0302 Cylinder 2 misfire detected Injector 2 excess emissions/catalyst damaging level of
misfire
P0203 Injection circuit malfunction - cylinder 3 Injector 3 open circuit
P0267 Cylinder 3 injector circuit low Injector 3 short circuit to earth
P0268 Cylinder 3 injector circuit high Injector 3 short circuit to battery supply
P0303 Cylinder 3 misfire detected Injector 3 excess emissions/catalyst damaging level of
misfire
P0204 Injection circuit malfunction - cylinder 4 Injector 4 open circuit
P0270 Cylinder 4 injector circuit low Injector 4 short circuit to earth
P0271 Cylinder 4 injector circuit high Injector 4 short circuit to battery supply
P0304 Cylinder 4 misfire detected Injector 4 excess emissions/catalyst damaging level of
misfire
P0205 Injection circuit malfunction - cylinder 5 Injector 5 open circuit
P0273 Cylinder 5 injector circuit low Injector 5 short circuit to earth
P0274 Cylinder 5 injector circuit high Injector 5 short circuit to battery supply
P0305 Cylinder 5 misfire detected Injector 5 excess emissions/catalyst damaging level of
misfire
P0206 Injection circuit malfunction - cylinder 6 Injector 6 open circuit
P0276 Cylinder 6 injector circuit low Injector 6 short circuit to earth
P0277 Cylinder 6 injector circuit high Injector 6 short circuit to battery supply
P0306 Cylinder 6 misfire detected Injector 6 excess emissions/catalyst damaging level of
misfire
P0207 Injection circuit malfunction - cylinder 7 Injector 7 open circuit
P0279 Cylinder 7 injector circuit low Injector 7 short circuit to earth
P0280 Cylinder 7 injector circuit high Injector 7 short circuit to battery supply
P0307 Cylinder 7 misfire detected Injector 7 excess emissions/catalyst damaging level of
misfire
P0208 Injection circuit malfunction - cylinder 8 Injector 8 open circuit
P0282 Cylinder 8 injector circuit low Injector 8 short circuit to earth
P0283 Cylinder 8 injector circuit high Injector 8 short circuit to battery supply

ENGINE MANAGEMENT SYSTEM - V8
18-2-38 DESCRIPTION AND OPERATION
Fuel pump relay
The fuel pump relay is located in the engine compartment fuse box. It is a 4 pin normally open relay. Input from the
ECM allows the fuel pump relay to control the electrical input to the fuel pump, regulating the fuel supply to the fuel
injectors. When the ignition is switched on and the engine is cranked, the fuel pump relay is activated by the ECM,
allowing the fuel system to be pressurised to 3.5 bar (52 lbf.in
2). The ECM then deactivates the relay until the engine
has started.
If the fuel pump runs, but the fuel pressure is out of limits, adaptive fuel faults will be stored.
Input/Output
The input value for the relay windings is battery voltage, the input value for the switching contacts comes from fuse
10 in the engine compartment fuse box. The output control of the switching contacts is direct to the fuel pump motor,
and the relay windings are controlled by pin number 18 of connector C0635 of the ECM.
At ignition 'on' (position II) the fuel pump relay contacts remain open until the ECM supplies an earth path for the relay
windings via pin number 18 of connector C0635 of the ECM. At this point, the relay windings are energised, drawing
the relay contacts closed. This allows voltage from fuse 10 in the passenger compartment fuse box to pass directly
to the fuel pump.
The fuel pump relay can fail the following ways or supply incorrect signal:
lRelay drive open circuit.
lShort circuit to vehicle earth.
lShort circuit to vehicle supply.
lComponent failure.
In the event of a fuel pump relay failure any of the following symptoms may be observed:
lEngine stalls or will not start.
lNo fuel pressure at the fuel injectors.
The ECM performs three types of diagnostic test to confirm the fuel pump relay integrity:
lOutput short circuit to earth
lOutput short circuit to battery voltage
lOutput open circuit

ENGINE MANAGEMENT SYSTEM - V8
18-2-52 DESCRIPTION AND OPERATION
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.
Function
All of the ECM's internal diagnostic fault paths are monitored by the OBD system. Specific faults have their own
numeric code relating to certain sensors or actuators etc. These specific faults fall into two types, error codes (E xxx)
or cycle codes (Z xxx). E codes represent instantaneous faults and Z codes relate to codes generated after completion
of a drive cycle.
If an emission relevant fault occurs on a drive cycle, the ECM stores a temporary fault code, if the fault does not occur
on subsequent drive cycles the fault code stays as a temporary fault code. If the fault recurs on subsequent drive
cycles the ECM stores the fault code as a permanent code, and depending on which component has failed the ECM
will illuminate the MIL.
Immobilisation system
The ECM and the body control unit (BCU) security system comprise the immobilisation system.
The ECM and the BCU combine to prevent the engine from running unless the appropriate security criteria are met.
The ECM and the BCU are a matched pair, if either one is replaced for any reason, the system will not operate unless
the replaced unit is correctly matched to its original specification. TestBook must be used to reconfigure the
immobilisation system.
Conditions
The ECM operates immobilisation in three states:
l'New'.
l'Secure'.
l'No Code'.