Range Rover 2. Electrical Manual

SEQUENTIAL MULTIPORT FUEL INJECTION (SFI–V8)

CIRCUIT DIAGRAM

C509

Z132
Engine Control
Module (ECM)

S509

Z261
Ignition Coils

C525

1&6

2&3

4&7

5&8

C525

See Fuse Details

P125a
Engine Compart-
ment Fuse Box

F 26

20 A

C508

SEQUENTIAL MULTIPORT FUEL INJECTION (SFI–V8)

CIRCUIT DIAGRAM

P125a
Engine Compart-
ment Fuse Box

[15] Ignition Relay

C173

Z238
Body Electrical
Control Module
(BECM)

C502

C120

S134

C502

Not used

NAS
From VIN 370859

C106

C506

A1-4

RL15
[15]

See Power Distribu-
tion

SEQUENTIAL MULTIPORT FUEL INJECTION (SFI–V8)

CIRCUIT DIAGRAM

X320
Fuel Pressure
Sensor

C506B

C106B

C122

C106B

C506B

S502

Z132
Engine Control
Module (ECM)

C507

A1-9

NAS
from model year
98

A1-9

Partial

DIESEL

CIRCUIT OPERATION

CIRCUIT OPERATION

Sensors

Engine Speed Sensor (X255)

The engine speed signal is crucial to the system, as
the information from the sensor is used in virtually all
of the strategies within the ‘DDE’ (Digital Diesel
Electronics) and its Engine Control Module (ECM)
(Z132). Through this sensor, the ECM (Z132) knows
if the engine is turning, how fast it is turning and
approximately where the engine is in its cycle. The
sensor is of the ‘Hall effect’ type, which sends out a
pulse to the ECM (Z132) every time a ‘tooth’ is
sensed on the flywheel (the flywheel has six ‘teeth’).
If the sensor fails, then the warning lamp is activated
and the ECM (Z132) enters a ‘limp home’ mode
where the ECM (Z132) looks at the signal from the
needle lift sensor in one of the injectors. The needle
lift sensor gives one pulse per injection, i.e. one
pulse per twelve engine speed sensor pulses. The
response of the ECM (Z132) to changes in engine
parameters will, therefore, be considerably slower,
and a higher idle speed is initiated to try to
compensate at low engine speeds.

Needle Lift Sensor (X318)

The engine has six diesel fuel injectors, one of which
has a sensing element at the tip which informs the
ECM (Z132) exactly when the injector fires (the
‘beginning of injection’ signal). The ECM (Z132) uses
this to correct the injection timing and also to back
up the engine speed signal in case that sensor fails.
If this sensor fails, the warning lamp will switch on
and the vehicle will enter ‘limp home’ mode with
reduced engine power/performance and lack of
throttle response (as there is a lack of feedback on
the injection timing).

Engine Coolant Temperature Sensor (X126)

This sensor is a ‘thermistor’ (a temperature
dependent resistor) where the voltage output varies
in proportion to coolant temperature. The ECM
(Z132) uses this information in many strategies, i.e.
to correct the injected fuel quantity and timing
(especially during cold starts), length of glow plug
timing, etc. The sensor is located in the top of the
engine block. In case of a failure, the warning lamp
is not activated and the ECM (Z132) selects a
substitute value of 50

C for glow plug and ignition

timing and uses the fuel temperature to correct the
fuel quantity, glow plug timing will not be correct,
possibly resulting in long crank times in cold weather

as well as slight fuelling effects. These symptoms
may not be noticeable.

Air Temperature Sensor (X311)

This sensor is another thermistor, located in the inlet
manifold, just after the intercooler, and measures the
actual temperature of the turbo booster air entering
the engine. To calculate the maximum amount of
injected fuel allowed, the ECM (Z132) needs to know
the volume of air flowing into the engine. Normally a
bulky, heavy and expensive air flow meter is
necessary, but the ECM (Z132) can calculate the air
flow from the air temperature and air pressure, so
eliminating the need for an air flow meter. If the air
temperature sensor fails, a substitute value of 30

is used, so by producing an incorrect air flow reading
and a reduction in engine power.

Range Rover 2. Electrical Manual - part 9