Land Rover Discovery: Electric Cooling Fan
- Fan shroud
- Cooling fan motor
- Electrical connection
- Speed flaps
An electric, variable speed cooling fan is installed in a shroud attached to
the rear of the radiator. The cooling fan is operated by an electric cooling
fan control module, integrated into the electric motor, under the control of
the ECM via a PWM signal. An electrical connector at the right side of the
shroud provides the interface between the cooling fan harness and the
vehicle wiring.
The electric cooling fan control module is provided with:
- A battery power supply from the engine junction box (EJB)..
- An ignition signal from the ECM relay in the EJB.
- A PWM signal from the ECM.
- A ground.
The ECM varies the PWM signal to the fan control module between 0 and
100% to operate the fan motor in one of four modes:
- Off
- Minimum speed (750 rev/min).
- Linear variable speed between minimum and maximum speeds.
- Maximum speed (2820 rev/min).
Under hot operating conditions, the electric cooling fan may continue to
operate for up to five minutes after the engine has been switched off.
The system is protected against abnormal internal temperature by
measuring its internal temperature at two points with temperature sensors.
- Sensor 1 : This sensor is used to calculate the temperature of active
components near the micro controller. The fan will stop immediately if the
fan internal temperature reaches 135ºC (275ºF). At motor stop, after a
delay of 120 seconds the diagnostic feedback will be sent. Normal
operation will resume once the temperature is less than 120ºC (248ºF).
- Sensor 2 : This sensor is used to measure the temperature of the power
stage of the PCBA (near the metal oxide semi-conductor field effect
transistors (MOSFETs)) to reduce the power if the temperature is too high
(derating) and to stop the motor in case of an over temperature condition
The fan will derate if the powerstage internal temperature reaches 135ºC
(275ºF) and stop motor function at 145ºC (293ºF). At motor stop, after a
delay of 120 seconds the diagnostic feedback will be sent. Normal fan
operation will resume once the powerstage temperature falls to 135ºC
(275ºF).
COOLANT EXPANSION TANK
- Pipe connection - coolant expansion line from radiator
- Pipe connection - coolant expansion line from engine thermostat housing
- O-ring seal
- Cap
- Bolt and washer
- Coolant expansion tank
- Location grommet
- Coolant level sensor
- Hose connection to coolant pump
The coolant expansion tank is located in the left side of the engine
compartment. The tank is located by a grommet on its underside and
positively secured with a bolt and washer to a bracket on the vehicle body
and a second bracket that locates in a molded slot in the tank body.
The coolant expansion tank has three connections; one for radiator bleed,
one for engine bleed and one for outlet to the thermostat housing.
An engine coolant level sensor is located in the underside of the tank body.
The sensor reacts to the influence of a magnetic field. A float, with integral
magnet, is located inside the tank, over the sensor tube. The sensor has
contacts inside the tube, which are normally open. When the fluid level
reduces, the magnetic float moves down the tube. When the magnet
reaches the sensor contacts, the magnetic field closes the contacts. The
sensor connects hardwired to the Central Junction Box (CJB) which receives
the signals from the sensor. Maximum and minimum marks are molded on
the tank body.
The coolant expansion tank provides the following functions:
- Service fill.
- Coolant expansion during warm-up
- Air separation during operation.
- System pressurization by the filler cap.
READ NEXT:
Thermostat housing
Heater element
Temperature sensor
The electric thermostat independently controls the engine coolant flow to
the cylinder head and cylinder block, improving engine warm-up tim
PRINCIPLES OF OPERATION
For a detailed description of the Engine Cooling system, refer to the
relevant Description and Operation section in the workshop manual.
REFER to: Engine Cooling (303-03B Engi
REMOVAL
WARNING:
Make sure to support the vehicle with axle stands.
Raise and support the vehicle.
Refer to: Diesel Exhaust Fluid Tank Drain and Refill (303-08B Engine
Emission Control - INGENIUM I4 2
SEE MORE:
The CJB controls the exterior lighting system through interconnections as
follow:
Left steering column multifunction switch
Side lamp position
Low beam position
Automatic ('AUTO') position (if fitted)
Front fog lamp switch (if fitted)
Rear fog lamp switch
Turn signal indicators
High beam sw
A number of vehicle features and display
settings may be configured via the
Instrument panel menu.
To display and navigate through the
Instrument panel menu, operate the menu
control on the steering wheel.
Steering wheel menu control: Press to
activate the menu, then use as follows:
Press t