It's actually wired into the 12v aux, I already have my ramps fan wired into D9, but then I suppose, I could change the connectors around, and have the extruder fan into D9 and then the Ramps fan into the 12v aux port. But I only ever have my that fan on when there is a print running.
![ramps1.4-1.jpg]( "ramps1.4-1.jpg")
![ramps1.4-2.jpg]( "ramps1.4-2.jpg")
