Ive got ground noise coming through my radio. Only when the trucks running and only when the radio itself is on. It doesnt do it if I have a CD on. I had pulled my antenna off once and found rust in there. I cleaned it out as best i could and put a little bit of di-electric grease in there. Still didnt help so i tried cleaning it all out again and bought a new antenna. Still no luck.

 

Could be your spark plugs or wires giving interferance. This WILL do that.