Standard Aftermarket Car Stereo Head Unit Wire Colors
The easiest way to wire in an aftermarket car stereo is to identify the OEM wires using diagrams for the specific vehicle and head unit. Still, it’s possible to get the job done without any labels, adapters, or diagrams. Unlike OEM head units, which are all over the place in terms of wire colors, most aftermarket manufacturers stick to a standardized coloring scheme. Although there are exceptions to every rule, most aftermarket car stereos use a standardized coloring scheme for the power, ground, antenna, and speaker wires. Suppose you have the pigtail that came with your aftermarket head unit, and it uses the standard colors. In that case, the wires have the following purposes and colors:
Power Wires
Constant 12V / Memory Keep Alive: YellowAccessory: RedDimmer/illumination: Orange with a white stripe
Ground Wires
Ground: black
Speakers
Right front speaker(+): GrayRight front speaker(-): Gray with a black stripeLeft front speaker(+): WhiteLeft front speaker(-): White with a black stripeRight rear speaker(+): PurpleRight rear speaker(-): Purple with a black stripeLeft rear speaker(+): GreenLeft rear speaker(-): Green with a black stripe
Amplifier and Antenna Wires
Antenna: BlueAmplifier remote turn on: Blue with a white stripe
Installing a Used Car Stereo With or Without a Pigtail
If you have a used car stereo that you want to install and the pigtail that came with the head unit, check the list above to see what each wire in the pigtail needs to connect to. If you don’t have the pigtail, look for an adapter that’s designed to connect that head unit to your make and model of car. If that doesn’t work, obtain a replacement pigtail to proceed anyway. Hopefully, the colors of those wires will match up to the aftermarket standard. Otherwise, you’ll need a wiring diagram, which is sometimes printed on the exterior of the head unit or available online.
Using a Head Unit Harness Adapter
Although most aftermarket head units follow the above coloring scheme, and it’s possible to figure out what the OEM wires in your car are for without a wiring diagram, installing an aftermarket head unit is easier if you have a harness adapter. Car stereo wiring harness adapters are useful because, while aftermarket car stereos have the same inputs and outputs as the factory stereos that they’re designed to replace, those inputs and outputs aren’t in the same places. If you can get the correct car stereo wiring adapter, it simplifies the installation process. One end of the adapter plugs into the car stereo, the other end plugs into the wiring harness that originally connected to the factory stereo, and that’s all there is to it.
Why Doesn’t Everyone Use Harness Adapters Instead of Splicing Wires?
While harness adapters are inexpensive—and available for various car and head unit combinations—there isn’t much wiggle room in terms of compatibility. For a head unit wiring harness to work, it needs to be specifically designed for both the vehicle and the new head unit. Suppose you can figure out the specific model of the head unit that you’re trying to install. In that case, there are online resources that allow you to plug in that information—along with the make, model, and year of your car—to see if an adapter is available.
What if a Head Unit Wiring Harness Adapter Isn’t Available?
If you can’t figure out the specific model of a used head unit, identify the purpose of each wire and manually connect everything the right way. In that same vein, there is also a chance that an adapter isn’t available for any given combination of vehicle and head unit. If that’s the case, and you also don’t have the pigtail that came with the head unit, either find a replacement pigtail or track down a wiring diagram and connect to the individual pins on the back of the head unit. While you can install a head unit without a wiring harness, it’s more complicated than the sort of basic DIY head unit installation process that most do-it-yourselfers are comfortable with.
