Land Rover Range Rover Electrical Library Lm 2nd Edition Rover Manual

							DESCRIPTION AND OPERATION
4.46RANGE ROVER
ANTI-LOCK BRAKING SYSTEM (ABS)
DESCRIPTION
General
New Range Rover is equipped with Dynamic Stability Control (DSC) for enhanced braking 
and stability control. Functions of the DSC include:

Hill Decent Control (HDC).

Electronic traction control (ETC).

Anti-lock Braking System (ABS).
The DSC system for New Range Rover provides all of the following functions and features:

Optimised traction under all driving conditions.

Optimised directional control (Longitudinal Stability).

Lateral stability (Correction for over steer/under steer).

Corner Braking Control (CBC).

Emergency Brake Assist (EBA).

Electronic Brake Force Distribution (EBD).
For a detailed description of the ABS, HDC, and ETC systems, refer to the  Brakes  section 
of the System Description and Operation Workshop Manual.
OPERATION
Power Distribution
Feed from the positive battery terminal (C0192) is supplied to the following on R wires:

Fusible link 2 (C0632) – V8 vehicles only.

Maxi fuse 63 (C0632).

Fuse 13 (C0632).

Fuse 53 (C0632).

Fuse 55 (C0632).

Fuse holder (C1875) – Td6 vehicles only.
Maxi fuse 63 (C0580) and fuse 55 (C0583) provide constant battery feeds to the ABS ECU 
(C0506) on R and RB wires respectively. The ABS ECU is earthed on a pair of N wires. Fuse 
13 (0586) provides a constant battery feed to the steering angle sensor (C0862) on an RG 
wire.
Fuse 53 (C0583) provides a constant battery feed to the ignition switch (C0099 on Td6 
vehicles, C0028 on V8 vehicles) on an R wire. When the ignition switch is turned to the 
auxiliary position, current flows across the switch (C0099 on Td6 vehicles, C0028 on V8 
vehicles) to fuse 37 of the passenger compartment fuse box (C0585) on a PB wire. Fuse 37 
(C0587) provides an auxiliary ignition feed to the Dynamic Stability Control (DSC) switch 
(C0700), located on the centre console, on a GBY wire. 
						

							DESCRIPTION AND OPERATION
RANGE ROVER 4.47
V8
Fusible link 2 (C0632) provides a constant battery feed to the ECM relay (C1895) on an R 
wire. Operation of the ECM relay (C1895) is controlled by the ECM (C0604) on an N wire. 
The energised ECM relay (C1895) provides a feed to fuse 51 of the passenger compartment 
fuse box (C0584) on an RW wire. Fuse 51 (C0584) is connected to the ABS ECU (C0506) 
and the steering angle sensor (C0862) by a pair of RW wires.
Td6
The 100A fuse within the fuse holder (C1878) provides a constant battery feed to the ECM 
relay (C1895) on an R wire. Operation of the ECM relay (C1895) is controlled by the ECM 
(C0604) on an N wire. The energised ECM relay (C1895) provides a feed to fuse 51 of the 
passenger compartment fuse box (C0584) on an RW wire. Fuse 51 (C0584) is connected 
to the ABS ECU (C0506) and the steering angle sensor (C0862) by a pair of RW wires.
ABS
Wheel Speed Sensors
The ABS ECU (C0506) provides a feed to all four wheel speed sensors as follows:

To the LH front wheel speed sensor (C0516) on an R wire.

To the RH front wheel speed sensor (C0517) on a Y wire.

The LH rear wheel speed sensor (C0502) on a W wire.

To the RH rear wheel speed sensor (C0503) on a G wire.
The wheel speed sensors are hall effect sensors, and provide the ABS ECU with a square 
wave form signal. This signal rises and falls between approximately 2.5V and 0.75V. By 
measuring the frequency of the waveform, the ABS ECU can calculate the speed of the road 
wheel. The sensors provide the ABS ECU (C0506) with a wheel speed signal as follows:

From the LH front wheel speed sensor (C0516) on a UR wire.

From the RH front wheel speed sensor (C0517) on a UY wire.

From the LH rear wheel speed sensor (C0502) on a UW wire.

From the RH rear wheel speed sensor (C0503) on a UG wire.
DSC
DSC Switch
DSC is active as soon as the ignition switch is turned to the ignition position. DSC can be 
switched off by pressing the non-latching master switch located on the centre console. 
When the ABS ECU (C0506) receives a momentary feed from the DSC switch (C0700) on 
a BY wire, it suspends DSC operation. Pressing the switch a second time reinstates DSC. 
						

							DESCRIPTION AND OPERATION
4.48RANGE ROVER
Steering Angle Sensor
The steering angle sensor (C0862) receives a constant battery feed from fuse 13 of the 
passenger compartment fuse box (C0586) on an RG wire, and a feed from the energised 
ECM relay (C1895) via fuse 51 of the passenger compartment fuse box (C0584) on an RW 
wire. The sensor (C0862) is earthed on an NB wire.
The steering angle sensor (C0862) transmits steering angle and rate of steering messages 
via the Can bus on YN (low) and YB (high) wires. These signals are created by two 
potentiometers located within the sensor. The ABS ECU uses these messages to enable the 
DSC system control lateral stability.
Brake Fluid Level Warning Switch
If the brake fluid level is below the minimum level, DSC operation is suspended. The ABS 
ECU (C0506) monitors the condition of the brake fluid level switch (C0026) via an NGY wire.
HDC
The HDC switch (C0365) is mounted on the side of the gear selector lever, and is provided 
an auxiliary ignition feed from fuse 35 of the passenger compartment fuse box (C0587) on 
a GBY wire. The ABS ECU (C0506) monitors the condition of the HDC switch (C0365) via 
a BG wire.
EBA
Brake Pedal Switch
The brake pedal switch (C0075) is provided an auxiliary ignition feed from fuse 9 of the 
passenger compartment fuse box (C0587) on a PY wire. The ABS ECU (C0506) monitors 
the condition of the brake pedal switch (C0075) on a UR wire to enable it to operate its 
Emergency Brake Assist (EBA) function.
Diagnostic Socket
The diagnostic socket is located behind an access panel on the drivers side of the fascia. 
The ABS ECU (C0506) and the steering angle sensor (C0862) can be interrogated by T4 
via the K line bus on WP wires. 
						

							DESCRIPTION AND OPERATION
RANGE ROVER 4.49
SUPPLEMENTARY RESTRAINT SYSTEM (SRS)
DESCRIPTION
General
The Supplementary Restraint System (SRS) is controlled by the SRS Diagnostic Control 
Unit (DCU) which is mounted on the transmission tunnel, to the rear of the gear selector 
lever. The SRS DCU registers front and rear impacts via an integral accelerometer. Side 
impacts are registered via two side impact sensors; one mounted on the base of the RH B/
C post, one mounted on the base of the LH B/C post.
The drivers and passenger airbags can be deployed in one of two stages. A lesser impact 
will result in stage 1 deployment. Both the drivers airbag and the passenger airbag contain 
two squibs. Stage 1 entails the SRS DCU delaying deployment of the second squib for a split 
second. This results in a less severe deployment of the airbags. A larger impact will result 
in stage 2 deployment. This entails both squibs within the drivers and passenger airbags 
being deployed simultaneously.
Front head airbags are also mounted in the A post. These work in conjunction with the door 
mounted airbags. Rear head airbags, mounted in the D post are available as an option.
OPERATION
Power Distribution
Feed from the positive battery terminal (C0192) is supplied to fuse 53 of the passenger 
compartment fuse box (C0632) on an R wire. Fuse 53 (C0583) is connected to the ignition 
switch (C0099 on Td6 vehicles, C0028 on V8 vehicles) by an R wire. When the ignition 
switch is turned to the auxiliary position, current flows across the switch (C0099 on Td6 
vehicles, C0028 on V8 vehicles) to fuse 44 of the passenger compartment fuse box (C0585) 
on a PB wire. Fuse 44 (C0586) provides an auxiliary ignition feed to the following:

The SRS DCU (C0256) on a PU wire.

The LH seat belt buckle switch (C0100) on a PG wire.

The RH seat belt buckle switch (C0260) on a PG wire.

The occupancy detector sensor (C0962) on a PG wire. 
						

							DESCRIPTION AND OPERATION
4.50RANGE ROVER
Drivers Airbag
The drivers airbag can deploy in one of two stages, depending upon the severity of impact. 
If a less severe impact is detected, stage 1 deployment is carried out. The SRS DCU 
(C0256) provides a firing signal to the drivers airbag (C1254) via the rotary coupler (C0082) 
on a YB then S wire. The SRS DCU (C0256) provides an earth path for the drivers airbag 
(C1254) via the rotary coupler (C0082) on an LG then YN wire.
A split second later, the SRS DCU (C0256) provides a second firing signal to the drivers 
airbag (C1254) via the rotary coupler (C0082) on an SN then U wire. The SRS DCU (C0256) 
provides a second earth path for the drivers airbag (C1254) via the rotary coupler (C0082) 
on a US then SB wire.
When stage two deployment is required, the SRS DCU provides simultaneous firing signals 
to both squibs as described previously.
Passenger Airbag
The passenger airbag can deploy in one of two stages, depending upon the severity of 
impact. If a less severe impact is detected, stage 1 deployment is carried out. The SRS DCU 
(C0256) provides a firing signal to the passenger airbag (C0251) on a UN wire. The SRS 
DCU (C0256) provides an earth path for the passenger airbag (C0251) on a UB wire.
A split second later, the SRS DCU (C0256) provides a second firing signal to the passenger 
airbag (C0251) on a WB wire. The SRS DCU (C0256) provides an earth path for the 
passenger airbag (C0251) on a WN wire.
When stage two deployment is required, the SRS DCU provides simultaneous firing signals 
to both squibs as described previously
Door Airbags
The SRS DCU registers a side impact via the side impact sensors, which are mounted at 
the base of the LH and RH B/C posts. The SRS DCU monitors the condition of the RH 
sensor (C0951) and the LH sensor (C0950) on YR and YG wires respectively. Both sensors 
are earthed on NB wires. When the SRS DCU registers a side impact above its threshold 
level, it will fire the relevant door airbag.
The SRS DCU (C0256) provides a firing signal to the RH door airbag (C1499) on a U wire. 
An earth path is provided by the SRS DCU (C0256) on an N wire.
The SRS DCU (C0256) provides a firing signal to the LH door airbag (C1499) on an N wire. 
An earth path is provided by the SRS DCU (C0256) on a Y wire. 
						

							DESCRIPTION AND OPERATION
RANGE ROVER 4.51
Head Airbags
The SRS DCU registers a side impact via the side impact sensors, which are mounted at 
the base of the LH and RH B/C posts. The SRS DCU monitors the condition of the RH 
sensor (C0951) and the LH sensor (C0950) on YR and YG wires respectively. Both sensors 
are earthed on NB wires. When the SRS DCU registers a side impact above its threshold 
level, it will fire the relevant head airbag.
LH Front
The SRS DCU (C0256) provides a firing signal to the LH front head airbag (C1477) on a UY 
wire. An earth path is provided by the SRS DCU (C0256) on a Y wire.
RH Front
The SRS DCU (C0256) provides a firing signal to the RH front head airbag (C1478) on a W 
wire. An earth path is provided by the SRS DCU (C0256) on a UW wire.
LH Rear
The SRS DCU (C0256) provides a firing signal to the LH rear head airbag (C1474) on a B 
wire. An earth path is provided by the SRS DCU (C0256) on a Y wire.
RH Rear
The SRS DCU (C0256) provides a firing signal to the RH rear head airbag (C0948) on a UG 
then UR wire. An earth path is provided by the SRS DCU (C0256) on an R then G wire.
Occupancy Detector 
The occupancy detector determines if there is a passenger occupying the front seat. If the 
front seat passenger is not detected, the front passenger airbag, and front passenger head 
airbag deployment is suspended in the event of an impact. All other SRS components will 
operate as normal. 
The occupancy detector (C0962) is provided an auxiliary ignition feed from fuse 44 of the 
passenger compartment fuse box (C0586) on a PG wire, and is earthed on an NB wire. The 
occupancy detector (C0962) provides a pulsed voltage signal to the SRS DCU (C0256) on 
a WR wire. The signal consists of 7 bits. A signal of 0 00 00 01 informs the SRS DCU the 
front passenger seat is unoccupied. A signal of 0 11 11 01 informs the SRS DCU the front 
passenger seat is occupied.
Seat Belt Switches
The SRS DCU determines if the front seat belts are being used by monitoring the status of 
the seat belt switches. If the seat belt tongue is inserted into the buckle, the switch contacts 
close and battery voltage is supplied to the SRS DCU (C0256) on UW (LH) and UP (RH) 
wires. If the SRS DCU detects a seat belt is not being used, it will not fire the relevant seat 
belt pre-tensioner. 
						

							DESCRIPTION AND OPERATION
4.52RANGE ROVER
Seat Belt Pre-tensioners
If the SRS DCU detects a front or rear impact, it will deploy the front seat belt pre-tensioners. 
The SRS DCU (C0256) provides a firing signal to the RH seat belt pre-tensioner (C0252) on 
a UN wire. An earth path is provided by the SRS DCU (C0256) on a UR wire. The SRS DCU 
(C0256) provides a firing signal to the LH seat belt pre-tensioner (C0254) on a YR wire. An 
earth path is provided by the SRS DCU (C0256) on a YN wire.
Battery Disconnection
In the event of an impact severe enough to implement stage 2 airbag deployment, a 
pyrotechnic charge on the positive battery terminal will disconnect the battery. The SRS 
DCU (C0256) provides a firing signal to the battery (C2250) on an NR then B wire. An earth 
path is provided by the SRS DCU (C0256) on a B then N wire.
Body Control Unit (BCU)
In the event of an impact severe enough to trigger the SRS system, the SRS DCU (C0256) 
provides a pulsed voltage signal to the BCU (C0661) on an SU wire. The BCU then enters 
its crash mode, unlocking all the doors, illuminating the interior lamps, and powering the 
hazard warning lamps.
SRS Warning Lamp
The SRS DCU (C0256) controls operation of the SRS warning lamp (C0230) by providing a 
pulsed voltage feed on an NP wire. 
						

							DESCRIPTION AND OPERATION
RANGE ROVER 4.53
AUTOMATIC TEMPERATURE CONTROL (ATC)
DESCRIPTION
General
The Automatic Temperature Control (ATC) system is controlled by the ATC ECU, which is 
located behind the centre console. ATC features automatic control of a common 
temperature setting for both sides of the passenger compartment, with manual control of the 
blower speed, air recirculation, and air distribution.
A Fuel Burning Heater (FBH) is fitted as standard on Td6 vehicles, and as an option on V8 
vehicles. For more information on FBH operation, refer to the relevant  Fuel Burning Heater 
(FBH)  section of this manual.
 
+  FUEL BURNING HEATER – Td6. 
 
+  FUEL BURNING HEATER – V8. 
For more details on ATC operation, refer to the  Air Conditioning  section of the System 
Description and Operation Workshop manual.
OPERATION
Power Distribution
Feed from the positive battery terminal (C0192) is supplied to the following on an R wire:

Maxi fuse 61.

Maxi fuse 64.

Fuse 12.

Fuse 53.
All are located in the passenger compartment fuse box (C0632). Maxi fuse 61 (C0581) 
provides a constant battery feed to the cooling fan control unit (C0005) on an RU then U 
wire. Maxi fuse 64 (C0580) provides a constant battery feed to the blower motor control unit 
(C2281) on an RU then YG wire. 
Fuse 12 (C0586) provides a constant battery feed to the ATC ECU (C1630) on an RP wire. 
The ATC ECU (C1630) is earthed on an N wire.
Fuse 53 (C0583) provides a constant battery feed to the ignition switch (C0099 on Td6 
vehicles, C0028 on V8 vehicles) on an R wire. When the ignition switch is turned to the 
ignition position, current flows across the switch (C0099 on Td6 vehicles, C0028 on V8 
vehicles) to fuse 34 of the passenger compartment fuse box (C0585) on a G wire. Fuse 34 
(C0587) provides an ignition feed to the ATC ECU (C1629) on a GY wire. 
						

							DESCRIPTION AND OPERATION
4.54RANGE ROVER
Compressor
When compressor operation is required, the ATC ECU (C1629) sends a message to the 
Engine Control Module (ECM) via the K bus on a WRY wire. Provided there are no engine 
management constraints, the ECM (C0331) responds by increasing throttle angle and 
fuelling and returns a signal granting operation of the compressor to the ATC ECU (C1629) 
on a BG wire. The ATC ECU (C1630) then provides a feed to the compressor clutch (C0182) 
on a BS wire.
For more details of compressor operation, refer to the  Air Conditioning  section of the 
System Description and Operation Workshop manual.
Refrigerant Pressure Sensor
The refrigerant pressure sensor is located in the refrigerant line between the condenser and 
the thermostatic expansion valve. It provides the ATC ECU with a pressure input from the 
high pressure side of the refrigerant system. The ATC ECU (C1629) provides a 5 V 
reference feed to the pressure sensor (C1610) on a GY wire. The pressure sensor (C1610) 
returns a signal voltage of between 0 V and 5 V, depending upon system pressure, to the 
ATC ECU (C1629) on a BS wire. The ATC ECU (C1629) provides an earth path for the 
pressure sensor (C1610) on an NB wire.
Evaporator Temperature Sensor
The evaporator temperature sensor is a Negative Temperature Coefficient (NTC) sensor. 
The ATC ECU (C0923) provides a feed to the evaporator temperature sensor (C0417) on 
an NB wire. By measuring the voltage returned on a YB wire, the ATC ECU (C0923) can 
determine evaporator temperature.
Blower Motor
Operation of the blower motor is controlled by the ATC ECU via the blower motor control 
unit. To control blower motor speed, the ATC ECU (C0923) provides a stepped voltage of 
between 0 V and 8 V to the control unit (C2281) on a UR wire. This is used by the control 
unit to regulate the supply voltage from maxi fuse 64 of the passenger compartment fuse 
box to the blower motor (C0056) on BG and RG wires.
The blower motor control unit (C2281) is earthed on an N wire.
Heater Coolant Temperature Sensor
The heater coolant temperature sensor is a Negative Temperature Coefficient (NTC) 
sensor. The ATC ECU (C0923) provides a feed to the temperature sensor (C0416) on an 
NB wire. By measuring the voltage returned on the YR wire, the ATC ECU (C0923) can 
determine the temperature of the air exiting the heater matrix. 
						

							DESCRIPTION AND OPERATION
RANGE ROVER 4.55
Coolant Valve
A single coolant valve is fitted on the ATC system to control coolant flow to the heater matrix. 
The coolant valve (C2034) is controlled by a Pulse Width Modulated (PWM) signal from the 
ATC ECU (C1629) on a YN wire.
Auxiliary Coolant Pump
The auxiliary coolant pump is used to ensure a satisfactory flow rate through the heater 
matrix at low engine speeds. The ATC ECU (C1629) provides a feed to the pump (C2035) 
on a UG wire. The pump (C2035) is earthed on an N wire.
Cooling Fan
Operation of the cooling fan is controlled by the ECM. When the compressor is engaged, the 
ATC ECU (C1629) informs the ECM (C0331) via the K bus on a WRY wire that cooling fan 
operation is required. The ATC ECU also informs the ECM of the speed at which the fan 
should be driven. 
The ECM also monitors Engine Coolant Temperature (ECT) to determine fan speed. The 
ECM (C0606) provides a feed to the ECT sensor (C0169) on an SU (Td6) or YG (V8) wire. 
The ECT sensor is a Negative Temperature Coefficient (NTC) sensor. By measuring the 
voltage returned on an NG (Td6) or NO (V8) wire, the ECM can determine engine coolant 
temperature.
The ECM (C0331) now provides a feed to the cooling fan control unit (C0005) on a BG wire. 
This is used by the control unit to regulate the supply voltage from maxi fuse 61 of the 
passenger compartment fuse box (C0581) on an RU wire.