help me fix my ground loop :(
 

So basiclly I got a alpine w505 recently installed and had a pioneer f700bt. Basiclly with any deck there's a high pitch whine. So I looked it up and figured it was a ground loop so I poked around and got this.

When I plug the rca's (deck to amp) to the amp and only plug the positive part in, I get clear sound but when I plugged the entire thing including the neg terminal I get my ground loop. So what's the cure?

Both the amp and deck has been grounded. Deck to wireharness and amp to the chassis.

Thanks in advance

Try grounding the rca outer jacket.

Red RCA Versus white/black rca is not positive negative. Each RCA head has positive and negative, the inner peg of the head of the rca is positive, the outer peg is negative.
Either you have faulty RCA's or a Faulty Channel in your amp, try swapping left and right rca's. instead of red to red do red to white and white to red on one side and it should help determine the program, or call me and ask me, I always tell you to but you never do

^ LOL it's you have a business don't wanna bother... I'm weird hahaha if not I might come by later today/tmr :)

Just for giggles, disconnect the antenna and see if anything changes.

Grounding the outer jacket as Catalin suggested would be my first try.