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

							DESCRIPTION AND OPERATION
4.56RANGE ROVER
AUTOMATIC TEMPERATURE CONTROL (ATC) – COMFORT
DESCRIPTION
General
The Comfort Automatic Temperature Control (ATC) system is controlled by the ATC ECU, 
which is located behind the centre console. In addition to the features included on the low 
line system, the Comfort ATC system also features a second coolant valve, a pollution 
sensor, and a rear blower unit. 
The Comfort ATC system is fully automatic, with separate temperature settings for the LH 
and RH sides of the passenger compartment. Manual override is available for 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:

Fusible link 5.

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 wire. Maxi 
fuse 64 (C0580) provides a constant battery feed to the front 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. 
						

							DESCRIPTION AND OPERATION
RANGE ROVER 4.57
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 ignition position, current 
flows across the switch (C0099 on Td6 vehicles, C0028 on V8 vehicles) to fuse 34 and fuse 
2 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.
Fuse 2 (C0587) provides an ignition feed to the rear blower relay coil (C2022) on a GY wire. 
The rear blower relay is located in the rear fuse box (C2021) and is earthed on an N wire.
Fusible link 5 of the passenger compartment fuse box (C0588) provides a constant battery 
feed to fuse 12R in the rear fuse box (C2024) on an R wire. Fuse 12R is connected to the 
rear blower relay switch. When the relay is energised, current flows across the closed switch 
contacts (C2021) to the rear blower motor control unit (C2282) on a GU then SUY then UG 
wire.
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 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. 
						

							DESCRIPTION AND OPERATION
4.58RANGE ROVER
Sunlight Sensor
The sunlight sensor consists of a LH and a RH photoelectric cell that provide the ATC ECU 
with inputs of light intensity. These are used by the ATC to adjust blower speed, 
temperature, and air distribution. The ATC ECU (C1629) provides a feed to the sunlight 
sensor (C0790) on a YB wire. The LH photoelectric cell (C0790) returns a signal back to the 
ATC ECU (C1629) on a YR wire. The RH photoelectric cell (C0790) returns a signal back to 
the ATC ECU (C1629) on a YG wire. The ATC ECU (C1629) provides an earth path for the 
sensor (C0790) on a YN wire.
Pollution Sensor
The pollution sensor allows the ATC ECU to monitor the ambient air for the level of 
hydrocarbons and oxidized gases. The ATC (C1629) provides two feeds to the sensor 
(C1548). The first is on a U wire, and is used to heat the sensor. A second feed is provided 
on a Y wire. This is a 5 V reference voltage to the sensor itself. A signal voltage of between 
0 V and 5 V is returned from pin 3 of the sensor (C1548) to the ATC ECU (C1629) on an N 
wire. The ATC ECU (C1629) provides an earth path for the sensor (C1548) on a second N 
wire (pin 1 of the sensor connector).
Front Blower Motor
Operation of the front blower motor is controlled by the ATC ECU via the front blower motor 
control unit. To control front 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 front blower motor (C0056) on BG and RG wires.
The front blower motor control unit (C2281) is earthed on an N wire.
Rear Blower Motor
Operation of the rear blower motor is controlled by the ATC ECU via the rear blower motor 
control unit. The ATC ECU (C0923) receives an input voltage of between 1.25 V (blower off) 
and 5 V (maximum blower speed) from the rear blower motor thumbwheel (C0846) on an 
RB wire. The thumbwheel is a potentiometer located in the rear ATC control unit. The ATC 
ECU (C0923) determines the blower speed requested from the voltage received from the 
thumbwheel and provides a stepped voltage of between 0 V and 5 V to the control unit 
(C2282) on a B then R wire. This is used by the control unit to regulate the supply voltage 
from the rear blower relay (C2021) to the rear blower motor (C2279) on GY and N wires.
The rear blower motor control unit (C2282) is earthed on an N wire. 
						

							DESCRIPTION AND OPERATION
RANGE ROVER 4.59
Air Distribution Motors
Unless manually overridden, operation of the air distribution motor is controlled 
automatically by the ATC ECU. The ATC ECU (C2295) provides a feed to the following on 
BW wires:

The face level air distribution motor (C2133).

The screen air distribution motor (C2134). 

The footwell air distribution motor (C2135).
 The ATC ECU (C2295) provides an earth path for all three motors on B wires.
Air Recirculation Motor
Unless manually overridden, operation of the recirculation motor is controlled automatically 
by the ATC ECU, using inputs from the pollution sensor and/or if rapid passenger 
compartment cooling is required. The ATC ECU (C2295) provides a feed to the recirculated 
air motor (C0006) on a BW wire. The ATC ECU (C2295) provides an earth path for the motor 
(C0006) on a B wire. 
Heater Coolant Temperature Sensors
Two heater coolant temperature sensors are fitted on Comfort ATC systems; on RH one 
LH. Both sensors are Negative Temperature Coefficient (NTC) sensors. The ATC ECU 
(C0923) provides a feed to the RH (C2296) and LH (C0416) temperature sensors on a pair 
of NB wires. By measuring the voltage returned on a YU (RH) and YR (LH) wire, the ATC 
ECU (C0923) can determine the temperature of the air exiting both sides of the heater 
matrix.
Coolant Valves
Two coolant valves are fitted to Comfort ATC systems to control coolant flow to each side 
of the heater matrix. Both are controlled by Pulse Width Modulated (PWM) signals from the 
ATC ECU (C1629) on YN (LH) and YP (RH) wires.
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. 
						

							DESCRIPTION AND OPERATION
4.60RANGE ROVER
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. 
						

							DESCRIPTION AND OPERATION
RANGE ROVER 4.61
FUEL BURNING HEATER – Td6
DESCRIPTION
General
The Fuel Burning Heater (FBH) is mounted in the rear of the engine compartment on the 
passengers side, and is fitted as standard on Td6 vehicles. The FBH is an additional heater 
installed in the heater coolant circuit. The FBH can be operated without the engine running 
to pre-heat the passenger compartment and after the engine starts to reduce heater coolant 
warm-up time. The FBH also boosts the heater coolant temperature while the engine is 
running at low ambient air and engine coolant temperatures to maintain heater performance 
at an acceptable level.
For a detailed description of FBH 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 fuse 59 of the passenger 
compartment fuse box (C0632) on an R wire. Fuse 59 (C0582) provides a constant battery 
feed to the FBH (C0925) on an RY wire. The FBH (C0925) is earthed on an N wire.
FBH Receiver
A remote request for park heating is received by the TV antenna located in the RH rear 
window. This is relayed to the FBH receiver (C2229) by the antenna amplifier (C2228) on an 
R wire. The FBH receiver (C2046) then provides a feed to the FBH (C0926) on a WG wire 
informing the FBH to operate the park heating function.
FBH Pump
The FBH pump is mounted below the RH side of the fuel tank. The FBH (C0926) provides 
a Pulse Width Modulated (PWM) signal to the pump (C0920) on a BR wire. The pump is 
earthed on an N wire.
K Bus
The instrument pack (C0233) communicates with the Air Temperature Control (ATC) ECU 
(C1629) and the FBH (C0926) via the K-bus on a WRY wire to initiate FBH operation. For a 
detailed description of the parameters for operation, and the messages sent via the K bus, 
refer to the  Air Conditioning  section of the System Description and Operation Workshop 
manual. 
						

							DESCRIPTION AND OPERATION
4.62RANGE ROVER
FUEL BURNING HEATER – V8
DESCRIPTION
General
The Fuel Burning Heater (FBH) is mounted in the rear of the engine compartment on the 
passengers side, and is fitted as an option on V8 vehicles. The FBH is an additional heater 
installed in the heater coolant circuit. The FBH can be operated without the engine running 
to pre-heat the passenger compartment and after the engine starts to reduce heater coolant 
warm-up time. The FBH also boosts the heater coolant temperature while the engine is 
running at low ambient air and engine coolant temperatures to maintain heater performance 
at an acceptable level.
For a detailed description of FBH 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 fuse 59 of the passenger 
compartment fuse box (C0632) on an R wire. Fuse 59 (C0582) provides a constant battery 
feed to the FBH (C0925) and the FBH receiver (C2046) on a pair of RY wires. The FBH 
(C0925) is earthed on an N wire, FBH receiver (C2046) on an NB wire.
FBH Receiver
A remote request for park heating is received by the TV antenna located in the RH rear 
window. This is relayed to the FBH receiver (C2229) by the antenna amplifier (C2228) on an 
R wire. The FBH receiver (C2046) then provides a feed to the FBH (C0926) on a WG wire 
informing the FBH to operate the park heating function.
FBH Pump
The FBH pump is mounted below the RH side of the fuel tank. The FBH (C0926) provides 
a Pulse Width Modulated (PWM) signal to the pump (C0920) on a BR wire. The pump is 
earthed on an N wire.
Changeover Valve
The changeover valve isolates the heater coolant circuit from the engine coolant circuit. The 
changeover valve is a normally open solenoid. To close the valve, the ATC ECU (C1629) 
provides a feed to the valve (C2037) on an SB wire. The valve is earthed (C2037) on an NB 
wire. 
						

							DESCRIPTION AND OPERATION
RANGE ROVER 4.63
K Bus
The instrument pack (C0233) communicates with the Air Temperature Control (ATC) ECU 
(C1629) and the FBH (C0926) via the K-bus on a WRY wire to initiate FBH operation. For a 
detailed description of the parameters for operation, and the messages sent via the K bus, 
refer to the  Air Conditioning  section of the System Description and Operation Workshop 
manual. 
						

							DESCRIPTION AND OPERATION
4.64RANGE ROVER
COOLING FAN
DESCRIPTION
General
The electrically powered cooling fan is mounted on the front of the radiator and works in 
conjunction with the cooling fan mounted on the front of the engine. Operation of the cooling 
fan is controlled by the Engine Control Module (ECM). The ECM determines cooling fan 
operating strategy after receiving inputs of Engine Coolant Temperature (ECT) from the 
ECT sensor, and requests for extra engine cooling from the Automatic Temperature Control 
(ATC) ECU via the K bus.
For more information on ATC operation, refer to the  Automatic Temperature Control 
(ATC)  or  Automatic Temperature Control – Comfort  section of this manual.
 
+  AUTOMATIC TEMPERATURE CONTROL (ATC). 
 
+  AUTOMATIC TEMPERATURE CONTROL (ATC) – COMFORT. 
OPERATION
Power Distribution
Feed from the positive battery terminal (C0192) is supplied to maxi fuse 61, fuse 12, and 
fuse 53 of the passenger compartment fuse box (C0632) on an R wire. Fuse 12 (C0586) 
provides a constant battery feed to the ATC ECU (C1630) on an RP wire. Maxi fuse 61 
(C0581) provides a constant battery feed to the cooling fan control unit (C0005) on an RU 
wire. 
Fuse 53 (C0583) provides a constant battery feed to the ignition switch (C0099 on Td6 
vehicles, C0028 on V8 vehicles) by 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.
Cooling Fan – Td6
Operation of the cooling fan is controlled by the ECM. The ECM monitors Engine Coolant 
Temperature (ECT) to determine fan speed. The ECM (C0606) provides a feed to the ECT 
sensor (C0169) on an SU wire. The ECT sensor is a Negative Temperature Coefficient 
(NTC) sensor. By measuring the voltage returned on an NG wire, the ECM can determine 
engine coolant temperature. 
						

							DESCRIPTION AND OPERATION
RANGE ROVER 4.65
When the ATC ECU engages the A/C compressor clutch, 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 to drive the motor. For more information on A/C 
operation, refer to the  Automatic Temperature Control (ATC)  or  Automatic 
Temperature Control (ATC) – Comfort  section of this manual.
 
+  AUTOMATIC TEMPERATURE CONTROL (ATC). 
 
+  AUTOMATIC TEMPERATURE CONTROL (ATC) – COMFORT. 
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.
Cooling Fan – V8
Operation of the cooling fan is controlled by the ECM. The ECM also monitors Engine 
Coolant Temperature (ECT) to determine fan speed. The ECM (C0606) provides a feed to 
the ECT sensor (C0169) on a YG wire. The ECT sensor is a Negative Temperature 
Coefficient (NTC) sensor. By measuring the voltage returned on an NO wire, the ECM can 
determine engine coolant temperature.
When the ATC ECU engages the Air Conditioning (A/C) compressor clutch, 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 to drive the motor. For more 
information on A/C operation, refer to the  Automatic Temperature Control (ATC)  or  
Automatic Temperature Control (ATC) – Comfort  section of this manual.
 
+  AUTOMATIC TEMPERATURE CONTROL (ATC). 
 
+  AUTOMATIC TEMPERATURE CONTROL (ATC) – COMFORT. 
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.