I'm skipping ahead, and i saw a full wiring diagram was posted already. The best thing you could do (assuming the diagram wasnt available), is use a DMM to test each wire. The ground will be easy, the power will have above 12v at all times. The ignition wire ill only have power when the ignition is turned on.. I don't remember how i found my speaker wires, those were seperated in my mercedes and easily identified because there are 4 pairs.. I wired my 2003 Mercedes CLK430 because no shop down here would touch it and be liable.