Quote:
Originally Posted by Turbo_Bimmer
That small wire comes from the DME to control the speed of the fan. The DME sends a signal with a variable duty cycle to vary the speed.
According to the schematic, the output of the DME grounds the small wire through a resistor to drive the base of the PNP transistor inside the fan.
So, if you want to test the fan on the bench, you should apply 12V to the terminal corresponding to the positive big wire, ground to the negative big wire, and ground (continious or intermittent) to the corresponding terminal of the small wire with a current limitting resistor in serie (value around 50 to 100 ohms). If it doesn't turn, try to lower the value of the resistance.
The fan shoud turn. Don't let the fan turn for too long though, the transistor won't be in an correct air flow to cool down if tested on the bench.
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This is good information here for me thank you very much. I will perform this test later today if possible and report back with my findings. I would also like to point out there is no way in hell I will remove this fan to test it at this point cause it's awful to get to!