Matt are you only using one battery? I was having problems with my selector switch never shutting out one from the other and somehow water had seeped into it and was giving me similar feedback. I actually ended up removing it and just run my motor from my starting battery and my electronics from my fuse box to the deep cycle battery. I think what Dan was talking about was one off these
http://www.marine.com/product_info.php/products_id/6141