[slimthelineman]

The fan coming on is normal. This is going to sound really dumb but the power wire for the receiver cable of the mmm is in the center of the plug. It sounds as if your speedo is not getting any signal from your radio system even though the servo works cause the bec is powering the receiver. Try flipping the plug around and see if it works worth a try at least. I have even done this in haste at the track trying to make a race before. If that's not it I can't reall say what it is.