Range Rover 2. Electrical Manual - part 154

 

  Index      Land Rover     Range Rover 2 electrical troubleshooting manual (From Model 1997-1999 year)

 

Search            copyright infringement  

 

 

 

 

 

 

 



 

 

Content   ..  152  153  154  155   ..

 

 

Range Rover 2. Electrical Manual - part 154

 

 

KEY INFORMATION

i

Component is disconnected.

Backprobe harness connector

Component is connected.

Backprobe harness connector

Component is disconnected.

Probe component

Component is disconnected.

Probe harness connector

Probe inĆline connector

TERMINAL

NUMBER

DESIGNATION

50

Battery voltage: Ignition Switch

in position III

30

Battery voltage: supplied constantly

15

Battery voltage: Ignition Switch

in position II or III

R

Battery voltage: Ignition Switch

in positions I, II

31

Ground

CIRCUIT DIAGRAMS

Circuit diagrams are arranged so that

current flow is from the top of the diagram

(current source) to the bottom of the

diagram (ground).

D

D Only those components that work together

in the circuit are shown. If only part of a

component is used in the circuit, then only

that part of the component is shown.

D Remember:

Entire component

Part of a component

D

DIAGNOSIS

If the diagram is accompanied by text:

- Read the Circuit Operation before

proceeding with the electrical diagnosis.

- Read the Troubleshooting Hints before

performing the System Diagnosis.

- Tests follow the System Diagnosis

- When performing the System Diagnosis,

be certain that all components

disconnected in previous steps are

reconnected unless otherwise directed.

See Introduction (i) for additional

circuit diagram symbols.

DIESEL

A6

CIRCUIT OPERATION

1

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.

Mass Air Flow Sensor (X105)

The Mass Air Flow Sensor (X105) is a hot film
sensor which has a heated surface maintained by an
electrical current at a constant temperature. With
cool air flowing past the sensor, the volume of air
drawn into the intake manifold is measured by the
electrical current required to keep the temperature of
the hot film sensor constant. This data is used to
calculate the injected fuel volume and the rate of
Exhaust Gas Recirculation (EGR).

The intake air temperature is measured by a
thermistor with a negative temperature co–efficient
and measures the actual temperature of the turbo
booster air entering the engine. The ECM (Z132)
uses this information, in conjunction with the
manifold absolute pressure sensor, to determine the
volume of air being drawn into the engine.

DIESEL

A6

CIRCUIT OPERATION

2

Boost Pressure Sensor

The boost pressure sensor signal is used in
conjunction with the air temperature signal to
calculate volume air flow into the engine. The sensor
is located on the rear bulkhead, with the pressure
tap just after the charge air cooler. If the sensor fails,
a substitute value of 490 hPa is used by the ECM
(Z132), producing a reduction in power due to a fuel
quantity limiting to 21mg/stroke.

Throttle Position Sensor (X171)

The DDE system is a ‘Drive by Wire’ system i.e. the
throttle pedal does not directly control a throttle disc
or the amount of fuel injected into the engine, but
accelerator movements or ‘drivers request’ are
sensed and the information is passed to the ECM
(Z132). The ECM (Z132) calculates the maximum
allowable fuel quantity from the air flow into the
engine, engine speed, temperature, etc. It also
includes information from strategies such as smoke
limitation, active surge damping, automatic gear
change, fuel reduction, etc. to calculate the final
figure. When driving, if the ‘drivers request’ signal is
smaller than the maximum allowable quantity, then
the requested quantity is injected. However, if the
requested quantity is greater than the maximum
allowable, then the latter quantity is injected rather
than the driver’s demand. Therefore the Throttle
Position Sensor (X171) is very important to the
system. It is located within the cab, close to the
pedal assembly itself. The unit consists of a
potentiometer and has three outputs:

1. Throttle Position – pin 37 ECM (Z132)

The sensor outputs the pedal position to the ECM
(Z132), which uses the information as described
above.

2. Idle Position Switch – pin 25 ECM (Z132).

The sensor has a separate idle position switch which
informs the ECM (Z132) of the pedal status in the
form of a simple on/off signal. This information is
used by the ECM (Z132) to implement 



idle speed

control’ and other strategies i.e. 



overrun fuel

shut–off’.

3. Kick Down Switch.

This switch is currently not used.

Fuel Temperature Sensor

A thermistor is also located inside the injection
pump. The fuel temperature sensor signal is used to
adjust the quantity of injected fuel, especially during
temperature extremes. The signal is also used to
back up the Engine Coolant Temperature Sensor
(X126). If this sensor fails, the ECM (Z132) uses a

substitute value of 60



C and only slight effects on

fuelling may possibly be noted.

Fuel Quantity Feedback Sensor

Located within the injection pump, this sensor sends
the ECM (Z132) information regarding the actual
quantity of fuel injected. Failure of the sensor or
corrupted signals will illuminate the warning lamp
and cause the engine to stall or not start. A second
check, a plausibility check against the needle lift
sensor, also takes place.

DIESEL

A6

CIRCUIT OPERATION

3

Fuel Quantity Actuator

Once again located within the injection pump, this is
a moving magnet actuator, failure of which will cause
the engine to stall or not start as the ECM (Z132) will
activate the Fuel Shut–Off Solenoid (K111).

Injection Timing (Solenoid Valve Injection Timing
Device (K229))

This is another actuator within the injection pump.
The ECM (Z132) receives a signal from the needle
lift sensor and attempts to correct the injection timing
accordingly. If a change does not occur, then the
ECM (Z132) assumes a fault exists, activates the
warning lamp and reduces the quantity of injected
fuel.

Fuel Shut–Off Solenoid (K111)

The Fuel Shut–Off Solenoid (K111) shuts the engine
down if the ECM (Z132) detects a major fault.
Failure of the valve itself does not activate the
warning lamp, although if a short circuit occurs, the
engine will shut down.

Cruise Control

Due to the DDE system being 



drive by wire’, a

cruise control feature is supplied in the ECM (Z132)
itself. Activation is via the steering wheel switches to
a converter box and on a single line to the ECM
(Z132). Failure of the signal results in cruise control
not working.

Brake Switches

The ECM (Z132) has two brake inputs, each of
opposite polarity. Comparison of the polarity states
provides the ECM (Z132) with a brake sense (i.e. if
switch 1 high and switch 2 low going to switch 1 low
and switch 2 high) and so cancels cruise control. If
both switches are the same polarity, the ECM (Z132)
senses a fault and does not allow cruise control.

Vehicle Speed Signal

The ECM (Z132) takes this signal from the
Anti–Lock Brake System ECU (Z108) and uses the
information for cruise control and 



active surge

damping’. Failure of the signal results in cruise
disallowed and temporary lack of surge damping (i.e.
hard acceleration will cause the vehicle to surge
slightly). After 10 sec. a substitute value of 150 km/h

is used. Surging will reduce so as to be hardly
noticeable.

Theft Alarm

The ECM (Z132) has a simple on/off input regarding
the theft alarm. The ECM (Z132) will not allow the
engine to start once activated and will kill the engine
if activated up to 300 RPM (programmable). Over
300 RPM, the engine is unaffected.

Relays

The DDE engine management system on the diesel
vehicles uses four relays:

ECM (Z132) power supply (main relay), glow plug
relay, starter motor relay and fuel pump relay. Two
are located in the fuse box and two in the ECM
(Z132) box behind the battery.

 

 

 

 

 

 

 

Content   ..  152  153  154  155   ..