Originally posted by PurpleEK
you prob. have a bad factory amp located in the rear pass. sidepanel right above the wheel well..... if you get the bypass plug this should sove you problem
Is this a common problem on explorers? I have the whistling now that correlates with RPM as well. I thought somehow the ground thats in the stock harness wasn't good enough or something. What type of bypass plug do I need? Its pretty damn annoying and I've never had any kind of trouble with just a aftermarket headunit.