Ok, so I bought the relocation harness to move the stock radio to the trunk and make room for the new aftermarket deck. I bought the Metra 70-2003T, but theres no switched 12 volts in the harness. It came with a separate red wire, which I'm guessing is to use to tap into a power source. I cant find anything besides a constant 12V, which of course i dont want to use, I want the radio to turn on and off with the key. Anybody know where I'm supposed to tap?