Running the Mercedes PWM Cooling Fan

This is the radiator fan from a 2005 Mercedes M500. Par Number is A163 500 03 93. It is an 850W fan and is about the most powerful fan available for its thickness. It has an overall thickness of 3.6" without the controller. In the area of the controller it has an thickness of 4.2"
Overall width is 24.75" without mounting tabs. 27.25" with tabs
Overall height is 22.625"
Fan diameter is 20.75"
Fan containment ring diameter is 21.625"


Operation 5V PWM signal at 10 Hz. Many people report using 3 to 12V. I couldn't get it to run below 3.7V and it does run at 12V. 5 V is my suggestion.


0% duty cycle is fail safe mode - Fan runs at full speed
10% duty cycle - Fan is off
20% to 90% duty cycle - Fan is in normal operational mode


Connections


Red thick wire goes to circuit 30 live at all times. In this video connected directly to 30 amp power supply +14V.


Black thick wire goes to ground. In this video connected directly to 30 amp power supply ground.


Blue thin wire goes to circuit 15 live with key on. In this video connected directly to 30 amp power supply +14V.


White thin wire goes to the PWM source from engine computers. In this video it is connected to the output of a wave form generator.


In this video a scope is also connected to the PWM signal and to the 30 amp power supply ground. The wave form generator ground is also connected to the 30amp power supply ground.


Note wiring color changes for each different model and year. You will need to refer to wiring diagrams.


Also note when using a wave form generator with a square wave, you will need to offset the signal 100% to get the lower portion of the wave to be near 0 volts.


Also note that this is a Temic motor. Others run at different frequencies.