I bought my buick with a pioneer deck, amp, eq, and subs already installed. As a consequence, I have no idea how it is all wired up. There is an mp3 player cable running down from the back of the system, however it is not working. It seems to run up the back, split into two single wires, then attach to something. I cannot seem to figure out how to get out whatever it is i need to remove in order to access the rear of the deck.