Yes, on a Ford, the IAC gets constant +12V (ignition key on) power, and the Ground is controlled by the ECU using a PWM− signal at 300 Hz.
The Holley can control it by PWM+ with a Ground tied to the engine block, or it can get a +12V power source and control it with a PWM− signal.
In my personal experience, the Ford IAC, because of how it operates, will be more stable & perform better, if you supply it with a constant +12V
signal and a PWM− from the Holley ECU. I do not know why it works better, I just know we have tried it both ways, and it has always worked
better using a PWM− signal to control it. Also, in my personal experience, if you can use a GM IAC, it always works better than the Ford IAC.
The Holley can control it by PWM+ with a Ground tied to the engine block, or it can get a +12V power source and control it with a PWM− signal.
In my personal experience, the Ford IAC, because of how it operates, will be more stable & perform better, if you supply it with a constant +12V
signal and a PWM− from the Holley ECU. I do not know why it works better, I just know we have tried it both ways, and it has always worked
better using a PWM− signal to control it. Also, in my personal experience, if you can use a GM IAC, it always works better than the Ford IAC.
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