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

							DESCRIPTION AND OPERATION
4.66RANGE ROVER
HEATED REAR WINDOW (HRW)
DESCRIPTION
General
Operation of the Heated Rear Window (HRW) is controlled by the Automatic Temperature 
Control (ATC) ECU via the non latching HRW switch. After 10 minutes of operation, (when 
ambient temperature is –15 °C (5 °F) or above) or 17 minutes (when ambient temperature 
is less than –15 °C (5 °F)), the ATC ECU operates the HRW at low power for 60 minutes. 
During the 60 minutes, the ATC ECU cycles the HRW relay off for 80 seconds and on for 40 
seconds. If the HRW switch is pressed again during the low power phase, the ATC ECU 
returns the HRW to full power by keeping the HRW relay energised for 5 minutes. At the end 
of the 5 minutes the low power phase is repeated.
The ATC ECU outputs a K bus message when the HRW is active. The message allows the 
navigation computer to compensate for the effect of the magnetic field generated when the 
HRW is active. The BCU transfers the message onto the P bus for the door modules, which 
activate the door mirror heaters together with the HRW.
OPERATION
Power Distribution
Feed from the positive battery terminal (C0192) is supplied to fusible link 5 and fuse 53 of 
the passenger compartment fuse box (C0632) on an R wire. Fusible link 5 (C0588) is 
connected to fuse 9 of the rear fuse box (C2024) by an R wire. Fuse 9 provides a constant 
battery feed to the HRW relay, which is also located in the rear fuse box.
Fuse 53 of the passenger compartment fuse box (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 2 of the passenger compartment fuse box 
(C0585) on a G wire. Fuse 2 (C0587) provides an ignition feed to the HRW relay coil (C2022) 
on a GY wire. The earth path for the relay coil (C2022) is controlled by the ATC ECU (C1629) 
on a UN wire.
HRW
When the HRW switch is pressed, a momentary earth path (C1630) is created on an N wire. 
If all operational conditions are met (see Description above), the ATC ECU energises the 
HRW relay. The energised HRW relay (C2021) provides a feed to the HRW (C0381) on a B 
wire. The HRW (C0382) is earthed on an N wire. 
						

							DESCRIPTION AND OPERATION
RANGE ROVER 4.67
HEATED FRONT SCREEN (HFS)
DESCRIPTION
General
Operation of the Heated Front Screen (HFS) is controlled by the Automatic Temperature 
Control (ATC) ECU via the non latching HFS switch. 
When the engine is running and the HFS is selected, the ATC ECU illuminates the LED 
above the switch and energises the HFS relay attached to the passenger end of the fascia 
cross tube. If not already active, the ATC ECU also activates the A/C compressor and the 
blower, and sets air distribution to windscreen. After 10 minutes (when ambient temperature 
is –15 °C (5 °F) or above) or 17 minutes (when ambient temperature is less than –15 °C (5 
°F)), the ATC ECU extinguishes the LED and de-energises the heated front screen relay. 
After the heater times out or is switched off, the timer in the ATC ECU is reset to zero.
OPERATION
Power Distribution
Feed from the positive battery terminal (C0192) is supplied to fusible link 1 and fuse 53 of 
the passenger compartment fuse box (C0632) on an R wire. Fusible link 1 (C0592) provides 
a constant battery feed to the HFS relay (C0994) on an R 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 HFS relay coil (C0994) on a GY wire. The earth path 
for the relay coil (C0994) is controlled by the ATC ECU (C1629) on a UN wire.
HFS
When the HFS switch is pressed, a momentary earth path (C1630) is created on an N wire. 
If all operational conditions are met (see Description above), the ATC ECU energises the 
HFS relay. The energised HFS relay (C0994) provides a feed to the LH (C0247) and RH 
(C0246) heater elements on a pair of B wires. Both elements are earthed on N wires. 
						

							DESCRIPTION AND OPERATION
4.68RANGE ROVER
WIPERS AND WASHERS
DESCRIPTION
General
The wipers and washers system is controlled by the Body Control Unit (BCU) on receipt of 
requests made by the driver or the rain sensor unit (if fitted). All wiper functions for the front 
and rear wipers are controlled from a multifunction wash/wipe switch assembly located on 
the right hand side of the steering column.
Optional equipment on Range Rover includes a rain sensor. The sensor, located below the 
interior rear view mirror, detects rain drops on the windscreen and automatically operates 
the wipers in the intermittent mode. 
NOTE: The column stalk switch must be in the intermittent position for rain sensor controlled 
wiper operation.
The front wiper system has four stages of wiper operation with four different delay periods 
for intermittent wipe. The four stages are as follows:

Flick wipe

Intermittent

Normal (slow) speed continuous

Fast speed continuous.
The intermittent wiper delay periods change with the road speed, with the delay decreasing 
as the road speed increases. Normal continuous operation changes to intermittent operation 
when the vehicle is stationary. Fast speed operation changes to normal operation when the 
vehicle is stationary.
For a detailed description of the wipers and washers, refer to the  Wipers and Washers  
section of the System Description and Operation Workshop manual. 
						

							DESCRIPTION AND OPERATION
RANGE ROVER 4.69
OPERATION
Front
Power Distribution
Feed from the positive battery terminal (C0192) is supplied to fuse 26 and fuse 53 of the 
passenger compartment fuse box (C0632) on an R wire. Fuse 26 (C0583) provides a 
constant battery feed to the wiper delay ECU (C0546) on an RW 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 41 of the passenger compartment fuse box (C0585) on a PB wire. Fuse 41 
(C0586) provides an auxiliary ignition feed to the Body Control Unit (BCU) (C0660) on a PW 
wire, and the rain sensor (C0961) on a PR wire.
Rain Sensor 
The rain sensor (C0961) is mounted on the upper edge of the windscreen. It is provided an 
auxiliary ignition feed from fuse 41 of the passenger compartment fuse box (C0586) on a PR 
wire, and is earthed on an NB wire. The rain sensor (C0961) provides information to the BCU 
(C0660) via the K bus on a WRY wire. This information is used by the BCU to determine 
optimum wiper operation for the prevailing conditions. 
Steering Wheel Switch
The BCU (C0660) provides feeds to the steering wheel switches (C0278) on BW and BU 
wires. The steering wheel switch (C0278) is earthed on an NB wire. The BCU determines 
which function has been selected by the earth paths that are created by the switch. If slow 
wipe is selected, current on the BW wire flows across the switch to earth. If fast wipe is 
selected, current on both the BW and BU wires flows across the switch to earth. If 
intermittent wipe is selected, current on the BU wire flows across the switch to earth. 
The steering wheel switch also contains a rotary potentiometer to control the intermittent 
wipe function. The intermittent wipe setting is interpreted by the BCU (C0661) from the feed 
returned from the switch (C0278) on a BG wire.
When the BCU (C0661) senses that wiper operation is required, it provides a feed to the 
wiper delay ECU (C0546) on an NU wire. The wiper delay ECU (C0546) is earthed on an N 
wire and provides two feeds to the wiper motor (C0546) on BG and BN wires.
Washer
If the steering wheel switch is pulled towards the driver, current flows from the BCU (C0660) 
to the steering wheel switch (C0278) on an NP wire, and then to earth on an NB wire. 
Sensing this earth, the BCU (C0662) provides a feed to the washer pump motor (C0008) on 
a B wire. Current flows across the washer pump motor (C0008) to earth on an N wire. The 
BCU powers the washer pump motor for as long as the switch is held in position, and also 
powers the wipers at slow speed. 
						

							DESCRIPTION AND OPERATION
4.70RANGE ROVER
Rear
Power Distribution
Feed from the positive battery terminal (C0192) is supplied to fuse 27, fuse 53, and fusible 
link 5 of the passenger compartment fuse box (C0632) on an R wire. Fuse 27 (C0585) 
provides a constant battery feed to the BCU (C0662) on an RU wire. Fusible link 5 (C0588) 
is connected to fuse 10 of the rear fuse box (C2024) on an R wire. Fuse 10 (C2021) provides 
a constant battery feed to the rear screen wiper ECU (C0388) on an RW wire.
Fuse 53 of the passenger compartment fuse box (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 41 of the passenger compartment fuse box (C0585) on a PB 
wire. Fuse 41 (C0586) provides an auxiliary ignition feed to the rear screen wiper ECU 
(C0835) on a PR wire. The ECU is earthed on an N (C0388) and an NB (C0835) wire.
Rear Wiper ECU
Operation of the rear wiper and washer system is controlled by the rear wiper ECU, which 
is integral with the motor assembly. The ECU (C0835) monitors the condition of the steering 
wheel switch (C0278) by providing feeds on BW and BU wires. If a request is made for rear 
wiper or washer operation, an earth path is created on an NB wire.
The rear wiper ECU (C0835) receives a reverse gear selected signal from the Light Check 
Module (LCM) (C2040) on a UY wire. When the rear wiper ECU receives this feed it powers 
the rear wiper motor.
Washer
When the rear wiper ECU receives a washer request from the steering wheel switch, it 
provides a feed to the rear washer pump (C0021) on a BR wire. Current flows across the 
pump motor (C0021) to earth on an N wire. 
						

							DESCRIPTION AND OPERATION
RANGE ROVER 4.71
HEADLAMP WASH/WIPE
DESCRIPTION
General
Operation of the headlamp wash/wipe system is controlled by the Body Control Unit (BCU) 
via the headlamp wash/wipe relay. Headlamp wash/wipe is activated automatically when the 
ignition and the headlamps are switched on, and windscreen wash/wipe is selected via the 
column switch. The headlamp wipers will operate through four cycles, with the washer jets 
spraying twice. This operation is only carried out on the first windscreen wash/wipe request, 
and then every fifth request from then on. This sequence is reset when the ignition is 
switched off.
For more information on headlamp wash/wipe, refer to the  Wipers and Washers  section 
of the System Description and Operation Workshop Manual.
OPERATION
Power Distribution
Feed from the positive battery terminal (C0192) is supplied to fuse 28 and fuse 53 of the 
passenger compartment fuse box (C0632) on an R wire. Fuse 28 (C0582) provides a 
constant battery feed to the following on RS wires:

The headlamp wash/wipe relay (C2031)

The RH headlamp wiper motor (C1341)

The LH headlamp wiper motor (C1340).
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 41 of the passenger compartment fuse box (C0585) on a PB wire. Fuse 41 
(C0586) provides an auxiliary ignition feed to the BCU (C0660) on a PW wire. The BCU 
(C0662) is earthed on an N wire.
Headlamp Wash/Wipe Relay
When the BCU (C0661) determines a wash/wipe selection has been made, it provides a 
pulsed voltage feed to the headlamp wash/wipe relay (C2031) on a UB wire. The headlamp 
wash/wipe relay (C2031) is earthed on an NB wire. When this feed is received, circuitry 
contained within the relay converts this signal into a headlamp wash/wipe request and 
closes the relay switch contacts. This allows a feed to be provided to the RH headlamp 
motor (C1341) and the LH headlamp motor (C1340) on a pair of BN wires. Current flows 
across the motors to earth on N wires. 
						

							DESCRIPTION AND OPERATION
4.72RANGE ROVER
BRAKE AND REVERSE LAMPS
DESCRIPTION
Brake Lamps
The brake lamps are active with the ignition switch in the auxiliary or ignition positions. The 
Light Check Module (LCM) receives an input from the brake switch, which is used as a signal 
to activate the brake lamps. When Hill Descent Control (HDC) is active, the ABS ECU 
outputs a signal on a separate hardwired connection to the LCM to activate the brake lamps 
when the HDC function is operating.
For more information on brake lamp operation, refer to the  Exterior Lamps  section of the 
System Description and Operation Workshop Manual.
Reverse Lamps
The reverse lamps will operate when the ignition switch is in the ignition position. The LCM 
activates the reverse lamps on receipt of a message on the I Bus that reverse gear has been 
selected.
For more information on reverse lamp operation, refer to the  Exterior Lamps  section of 
the System Description and Operation Workshop Manual.
OPERATION
Power Distribution
Feed from the positive battery terminal (C0192) is supplied to fusible link 3 and fuse 53 of 
the passenger compartment fuse box (C0632) on an R wire. Fusible link 3 (C0589) provides 
a constant battery feed to the Light Check Module (LCM) (C0937) on an R 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 9 of the passenger compartment fuse box (C0585) on a PB wire. Fuse 9 
(C0587) provides an auxiliary ignition feed to the LCM (C2040) and the brake pedal switch 
(C0075) on a pair of PY wires. 
						

							DESCRIPTION AND OPERATION
RANGE ROVER 4.73
Brake Lamps
The LCM (C2040) monitors the condition of the brake pedal via the brake pedal switch 
(C0075) on a UR wire. When the brake pedal is pressed, the switch contacts close and an 
earth path is created on an NB wire. Sensing this, the LCM (C0937) provides a feed to the 
following on BU wires:

The RH brake lamp (C0125)

The LH brake lamp (C0121)

The Centre High Mounted Stop Lamp (CHMSL) (C0613).
All are earthed on N wires.
When HDC is functioning, the ABS ECU (C0506) outputs a signal to the LCM (C2040) on a 
YN wire. When the LCM receives this signal, it operates the brake lamps as described 
above. For more information on ABS operation, refer to the  Anti-Lock Braking System 
(ABS)  section of this manual, and the  Brakes  section of the System Description and 
Operation Workshop manual.
 
+  ANTI-LOCK BRAKING SYSTEM (ABS). 
Reverse Lamps
When reverse gear is selected, a message is sent from the Electronic Automatic 
Transmission (EAT) ECU (C1835) to the Engine Control Module (ECM) (C0604) via the 
CAN Bus on YN (low) and YB (high) wires. This message is relayed from the ECM (C0331) 
to the instrument pack (C0234) via the CAN Bus on YN (low) and YB (high) wires
When the instrument pack receives this message, it outputs a signal to the LCM (C2040) via 
the I Bus on a WSY wire. When the LCM (C2039) receives a reverse gear selected signal, 
it provides a feed to the following on WY wires:

The RH reverse lamp (C0455)

The LH reverse lamp (C0472).
Both lamps are earthed on N wires. 
						

							DESCRIPTION AND OPERATION
4.74RANGE ROVER
HEAD, SIDE AND TAIL LAMPS
DESCRIPTION
General
Operation of the head, side, tail, and side marker (NAS vehicles only) is controlled by the 
Light Check Module (LCM). The LCM receives inputs from other systems via the I Bus.
Two headlamp systems are available; Halogen or bi-xenon. The two types of headlamps 
share a common lense.
NOTE: NAS vehicles are fitted with headlamp lenses marked with a Department of 
Transport (DOT) rating.
The bi-xenon headlamps illuminate when an arc of electrical current is established between 
two electrodes within the bulb. The xenon gas sealed in the bulb reacts to the electrical 
exitation and the heat generated by the current flow. The causes the gas to produce a blue/
white light.
WARNING: The bi-xenon system generates up to 28000 volts and contact with this 
voltage could lead to fatality. Ensure the headlamps are switched off before working 
on the system.
For more details of headlamp operation, refer to the  Lighting  section of the System 
Description and Operation Workshop Manual.
OPERATION
Halogen System
Power Distribution
Feed from the positive battery terminal (C0192) is supplied to fuse 53, fusible link 3, and 
fusible link 4 on an R wire. All are located in the passenger compartment fuse box. Fusible 
link 3 (C0589) and fusible link 4 (C0590) provide constant battery feeds to the Light Check 
Module (LCM) (C0937 & C2039 respectively) on a pair of R wires. The LCM (C2039) 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 
auxiliary position, current flows across the switch (C0099 on Td6 vehicles, C0028 on V8 
vehicles) to fuse 9 of the passenger compartment fuse box (C0585) on a PB wire. Fuse 9 
(C0587) provides an auxiliary ignition feed to the LCM (C2040) on a PY 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 4 of the passenger compartment 
fuse box (C0585) on a G wire. Fuse 4 (C0587) provides an ignition feed to the LCM (C2040) 
on a GS wire. 
						

							DESCRIPTION AND OPERATION
RANGE ROVER 4.75
Light Check Module
The LCM (C2040) is located at the base of the RH A post, and monitors the condition of the 
fascia mounted rotary lighting switch (C0041) by providing a feed on an NB wire. The LCM 
can determine the position of the switch by sensing if a feed is returned on a Y (side lamps) 
or a B (headlamps) wire. The LCM also monitors the condition of the column mounted main/
dipped beam switch (C1832) via a U wire.
Side Lamps
If the LCM detects that side lamps have been selected, it provides a feed to the following:

To the RH side lamp (C0537) on an SU wire

To the LH side lamp (C0538) on an SG wire

To the RH tail lamp (C0125) on an SW wire

To the LH tail lamp (C0121) on an SP wire

The rear number plate lamp (C1495) on an SN and an SB wire

To the RH front side marker lamp (C0916) on an SU wire (NAS vehicles only)

To the RH rear side marker lamp (C0918) on an SU wire (NAS vehicles only)

To the LH front side marker lamp (C0917) on an SG wire (NAS vehicles only)

To the LH rear side marker lamp (C0919) on an SG wire (NAS vehicles only).
All are earthed on N wires.
Headlamp Dipped Beam
In addition to the lamps outlined in the side lamps section, the LCM will provide feeds to the 
following lamps if it detects that headlamp dipped beam has been selected:

To the RH headlamp dipped beam bulb (C0011) on a YU wire

To the LH headlamp dipped beam bulb (C0009) on a WG wire.
Both are earthed on N wires.
Headlamp Main Beam
In addition to the lamps outlined in the side lamps and headlamp dipped beam sections, the 
LCM will provide feeds to the following lamps if it detects that headlamp main beam has 
been selected:

To the RH headlamp main beam bulb (C0011) on a WU wire

To the LH headlamp main beam bulb (C0009) on a YG wire.
Both are earthed on N wires.