Engine Cooling Fan Control Module
The engine cooling fan control module is located on the rear of the cooling fan shroud. The control module is located in the shroud moulding and secured with a screw.
The engine cooling fan control module is controlled by the PCM using a Pulse Width Modulation (PWM) ground. A permanent battery voltage is supplied from a fused output from the Battery Junction Box (BJB) and the Engine junction box (EJB). The output is controlled by the PCM relay in the EJB. The relay is controlled by the PCM.
The PCM can control the speed of the fan motor operation using the PWM ground. The fan motor is used for engine cooling and air conditioning purposes.
The PCM determines when to operate the cooling fan from the Engine Coolant Temperature (ECT) sensors input and/or a cooling fan request from the Automatic Temperature Control Module (ATCM). The PCM also adjusts the fan speed to compensate for the ram effect of vehicle speed.
The PCM varies the duty cycle of the Pulse Width Modulation (PWM) signal to the cooling 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, and maximum speed (2820 rev/min). Under hot operating conditions, the fan may continue to operate for up to five minutes after the engine has been switched off.
The cooling fan control module monitors for over and under input voltage, a stalled motor and a partially stalled motor. If it detects any of these faults the cooling fan control module temporarily pulls the PWM signal to ground to notify the fault to the PCM. The length of time the PWM signal is pulled to ground varies between 2 and 8 seconds, depending on the fault. The cooling fan control module repeats the notification process at 5 second intervals until the fault is cleared. If there is more than one fault, only the highest priority fault is notified to the PCM. Fault priorities, in descending order, are over voltage, under voltage, stalled motor and partially stalled motor. The PCM records a related DTC (diagnostic trouble code) for faults notified by the fan control module and signals the instrument cluster on the high speed CAN powertrain systems bus to display a warning message.