Today at work I was installing an Edlebrock Pro Flo 4 XT fuel system in a GMC pickup when I came across this in the instructions. Simple knowledge for me but it is so utterly important I share this here. So everybody knows good advice from bad advice instead of just whose word to trust..I would just like to point out that the fan controllers are ground circuits that are on or off and don't PWM. But the size of the larger coil in the solenoids just takes so much more to charge and generates so much heavier of a collapsing field than anything a computer circuit can control. And that is why a HD relay or solenoid is NEVER driven directly by an ecu circuit. A relay that draws under 1a max is the limit for a computer circuit. Typically.