Radiator Cooling Fan Speed Sensor: Description and Operation
Engine Control ComponentsFan Speed Sensor (FSS)
The FSS is a Hall-effect sensor that measures the cooling fan clutch speed by generating a waveform with a frequency proportional to the fan speed. If the cooling fan clutch is moving at a relatively low speed, the sensor produces a signal with a low frequency. As the cooling fan clutch speed increases, the sensor generates a signal with a higher frequency. The PCM uses the frequency signal generated by the FSS as a feedback for closed loop control of the cooling fan clutch. For additional information on the cooling fan clutch, refer to the Cooling Fan Clutch.
Cooling Fan Clutch with Fan Speed Sensor (FSS):
Cooling Fan Clutch with FSS