Viscous Cooling Fan

WARNING: This page is about a different variant/trim than selected.

To control the viscous cooling fan, the PCM sends a Pulse Width Modulation (PWM) signal to the Viscous Cooling Fan Control Module (VCFCM). The PCM varies the duty cycle of the PWM signal between 0 and 100% to vary the clutch engagement and thus fan speed.

If the PWM signal is outside the 0 to 100% range,

The VCFCM interprets the signal as an open or short circuit
And runs the fan at minimum speed to make sure the fan does not overspeed.

If the electrical connections to the viscous fan are disconnected the fan is idle and the engine may overheat. The PCM records a related Diagnostic Trouble Code (DTC) for faults notified by the VCFCM and signals the BCM through the FlexRay bus. The BCM/GWM transmits the signal to the Instrument Panel Cluster (IPC) to display a warning message.

The signal goes through the HS CAN Human Machine Interface (HMI) systems bus.