Electric Cooling Fan

Courtesy of JAGUAR LAND ROVER NORTH AMERICA, LLC

There are 2 electric, variable speed cooling fans are installed in a shroud attached to the rear of the radiator. Each electric cooling fan is operated by the related engine cooling fan control module, which is integrated into the electric cooling fan motor. The Powertrain Control Module (PCM) controls the engine cooling fan control modules through a Pulse Width Modulation (PWM) signal. Electrical connectors at the right side of the shroud provide the interface between the electric cooling fan harnesses and the vehicle wiring.

Each engine cooling fan control module is provided with:

• A power supply from the Engine Junction Box (EJB).
• An ignition signal from the PCM relay in the EJB.
• A PWM signal from the PCM.
• A ground.

The system is protected against abnormal internal temperature by measuring its internal temperature at 2 points with temperature sensors.

• Sensor 1: This sensor is used to calculate the temperature of active components near the micro controller. The electric cooling fan stops immediately if the internal temperature reaches 135°C (275°F). At motor stop, after a delay of 120 seconds the diagnostic feedback is stored. Normal operation resume when the temperature is less than 120°C (248°F).
• Sensor 2: This sensor is used to reduce the power and to stop the motor in case of an over temperature condition.

The electric cooling fan derates if the powerstage internal temperature reaches 135°C (275°F) and stop motor function at 145°C (293°F). At motor stop, after a delay of 120 seconds the diagnostic feedback is stored. Normal fan operation resume when the powerstage temperature falls to 135°C (275°F).

To control each electric cooling fan, the PCM varies the duty cycle of the PWM signal.

• The cooling fan control module translates the duty cycle into an electric cooling fan target speed
• And sets the output current to the electric cooling fan motor accordingly.