Aftermarket head unit wiring?

[Gonin60]

If I add an aftermarket hu and replace the rest of the system, do I need to buy the wiring harness? If so why?

[Azlandshark]

You need some sort of harness unless you want to cut off your factory plugs. You could buy the basic harness that allows you the constant 12v. ground, and then you will need to tap into a switchable 12v source. If your going to use a HU that has navigation you may need to tap into the speed sensor wire. The C2R CHY from Pac Audio will allow you to have all the above including brake, reverse, speed sensor, 12v constant, 12v switch, and ground. I replaced everything in my car and used the C2R CHY harness, I will also be adding steering wheel controls to the after market unit, so I will need to buy the SWI CAN and ECL2 "harness" in order to do so. There are many benefits from useing the harness. The biggest one is if you decide to sell the car, and you want to put iback to stock will be every easy. The next being the obvious, you have everything you need right there.