I was installing the 420 today and hooked everything up. The problem I am having is that my inner knob controls the tower and the outer knob controls the in boat speakers. I have checked the connects many times and there are hooked up correctly. If i switch the hookup so that they are connected incorrectly but so that the knobs work then the mic will not work and emits a very high pitched sound out of the in boat speakers.
What is my problem?