How to Identify Aftermarket Car Stereo Wire Colors

wires
PM Images / Digital Vision / Getty

The easiest way to wire in an aftermarket car stereo is to look at car stereo wiring diagrams for the specific vehicle and head unit, but it's actually possible to get the job done without any labels, adapters, or diagrams.

The reason you usually don't actually need a wiring diagram to install a car stereo, even if it's a second-hand unit that didn't come with any paperwork, is that aftermarket car stereo wire colors are actually pretty uniform. Unlike OEM head units, which are all over the place in terms of wire colors, there’s actually a standardized coloring scheme that most aftermarket manufacturers stick to.

Installing a Used Car Stereo With or Without a Pigtail

If you find yourself with a used car stereo that you want to install, and you have the pigtail that came with the head unit, then it's usually just a process of checking out the list in the next section of this article to see what each wire in the pigtail needs to connect to.

If you don’t have the pigtail, your best option is to look for an adapter that’s designed specifically to connect that head unit to your make and model of car. Failing that, you’ll have to obtain a replacement pigtail to proceed anyway, and 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.

Standard Aftermarket Car Stereo Head Unit Wire Colors

Although there are exceptions to every rule, most aftermarket car stereos use a standardized coloring scheme for the power, ground, antenna, and speaker wires. If you have the pigtail that came with your aftermarket head unit, and it uses the standard colors, then the wires will have the following purposes and colors:

  1. Power Wires
    1. Constant 12V / Memory Keep Alive — yellow
    2. Accessory — red
    3. Dimmer/illumination — orange w/white stripe
  2. Ground Wires
    1. Ground — black
  3. Speakers
    1. Right front speaker(+) — gray
    2. Right front speaker(-) — gray w/black stripe
    3. Left front speaker(+) — white
    4. Left front speaker(-) — white w/black stripe
    5. Right rear speaker(+) — purple
    6. Right rear speaker(-) — purple w/black stripe
    7. Left rear speaker(+) — green
    8. Left rear speaker(-) — green w/black stripe
  4. Amplifier and Antenna Wires
    1. Antenna — blue
    2. Amplifier remote turn on — blue w/white stripe

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 all for without a wiring diagram, installing an aftermarket head unit is much easier if you have a harness adapter.

The reason that car stereo wiring harness adapters are so useful is that while aftermarket car stereos have all the same inputs and outputs as the factory stereos that they're designed to replace, those inputs and outputs aren't all in the same places.

If you can get your hands on the right car stereo wiring adapter, it vastly 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?

The problem is that while harness adapters are fairly inexpensive, and they're available for a wide variety of car and head unit combinations, there really isn't any wiggle room in terms of compatibility. For a head unit wiring harness to work, it needs to be specifically designed for both your vehicle and your new head unit.

If you can figure out the specific model of the head unit that you’re trying to install, there are online resources out there where you can plug that in, 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, then you're better off identifying the purpose of each wire and just manually connecting everything the right way.

In that same vein, there is also a chance that there just isn't an adapter available for any given combination of vehicle and head unit. If that happens to be the case, and you also don’t have the pigtail that came with the head unit, then you’re either going to have to get your hands on a replacement pigtail or go through the process of tracking down a wiring diagram and connecting to the individual pins on the back of the head unit.

While it is technically possible to install a head unit without a wiring harness, it is a whole lot more complicated than the sort of basic head unit installation process that most do-it-yourselfers are comfortable with.