Quote:
Originally Posted by andrewb70
Scott,
Have you tried using PWM- like we have done with the C6 fan controllers?
Andrew
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Andrew,
Thanks for responding. I think I should have explained my question better.
The fan is definitely PWM controlled. The question is, what is the nature of the modulated signal? For instance, you can pulse a +12V signal, or pulse a ground connection (some aftermarket ECUs control analog gauges this way, for instance). And some kinds of PWM control "invert" the logic, e.g. wider pulses can mean slower speed instead of faster.
The GM ECUs have 3 kinds of PWM configuration: PWM Electrical, PWM EV, and PWM MRF, as they are called in HPTuners. I'm quite sure that PWM Electrical is a modulated +12V signal, but I don't know what the others do, specifically the PWM EV signal for controlling the CTSV fan. Don't want to damage an ECU or fan controller by guessing wrong.
BTW, PWM EV is apparently so named because it's the signal type used to control the "electro-viscous" fan clutches on some trucks. I'm guessing by what I can Google that this could be a modulated ground, but I'm hoping someone with more GM ECU hands-on can clarify.
Thanks much,
Scott