F 350 4WD Super Duty V8-6.0L DSL Turbo VIN P (2004)
Radiator Cooling Fan Speed Sensor: Description and Operation
FAN SPEED SENSOR (FSS)
The fan speed sensor is a Hall-Effect sensor integral to the vistronic drive fan (VDF). The PCM will monitor the sensor input and control the VDF speed
based upon engine coolant temperature (ECT), transmission fluid temperature (TFT) and intake air temperature (IAT) requirements. When an increase in
fan speed for vehicle cooling is requested, the PCM will monitor the FSS signal and output the required pulse width modulated (PWM) signal to a fluid
port valve within the VDF.