Car Stereo Help - Wire Color Codes - Wire Diagrams and Why aftermarket wire harness with aftermarket stereo? Both wire harnesses match color for color, hook up is easy, plug and play. Factory color codes are Not universal. We discourage cutting the factory wire harness. This section aids troubleshooting wire problems and installation of external devices. Car Stereo Wiring Diagrams and Car Radio Wiring Diagrams Car Stereo Wiring Diagrams and Car Radio Wiring Diagrams. Whether your an expert installer or a novice enthusiast, an automotive wiring diagram can save yourself time and headaches. One of the most time consuming tasks with installing an after market car stereo, car radio, car speakers, car subwoofer, car amplifier, mobile amp,..