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I'm planning to add a manual control switch for the radiator Hydraulic fan. the purpose is to switch it to high speed manually

From the service manual I found that the fan is controlled by the Front Control Module, and the Fan Solenoid has three pins (+fused, ground, and control)

and as per the service manual quoted below, the signal is PWM (Pulse With Modulated)

Anyone have ever tried to do similar job? ,,

Will simple 12V single or ground in the control pin will do the job?

The hydraulic radiator cooling fan used on the 5.7L and 3.0L Diesel engines replaces both the electric fan and the engine driven mechanical fan. This provides 5.7L and 3.0L Diesel equipped vehicles with heavy trailer towing capability while at the same time reducing unnecessary power drain on both the engine and the vehicles electrical system.

The hydraulic radiator cooling fan is controlled by the FCM. A PWM (Pulse With Modulated) signal from the JTEC controls the fan speed. There are four inputs to the FCM that determine what speed percentage of fan is required by the vehicle. These inputs are:

Engine Coolant Temperature
Transmission Oil Temperature
A/C System Pressure
By monitoring these three parameters, the FCM can determine if cooling airflow is required. If airflow is required, the FCM will slowly ramp up (speed up) the fan speed until the parameter(s) are under control. Once the temperature or pressure is reduced to within operating parameters the fan will ramp up, ramp down, or hold its speed to maintain the temperature / pressure requirements.

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