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What Is ACC Wire for Car Stereo?

Do you know what is ACC wire for a car stereo? If not, you’re not alone. But, unfortunately, many people don’t know what all the extra cables in their car are for.

But one of those cords could be very important for your audio system. So let’s look at what ACC wire is and why it matters for your car stereo.

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The 12V ACC wire tells the car stereo that the system is powered and is necessary for activating the car stereo. Typically, the ACC wire is red and thinner than the main power.

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Tip: ACC wires are part of the stereo harness, but if your radio does not have one, you can find a large selection of any harness types from Red Wolf or Scosche (links to Amazon).

In the article below, I will detail how to connect the ACC wire to your car stereo.

What Is ACC Wire in Car Radio?

The ACC wire in the car radio provides power to the stereo. 

This wire is typically red and is thinner than the primary power wire. The ACC wire must be connected to the ignition or cigarette lighter to activate the stereo.

How to Connect ACC Wire?

When installing the radio, the ACC wire has to be connected with the rest of the wires coming out of the stereo harness. However, in most car audio installations, there is not much to do but plug the stereo harness into the dash harness.

If you do not have a harness or the car does not have an accessory wire, you must connect it manually. To do it correctly, follow the steps below:

#1. Locate the ACC wire on your car stereo. The ACC wire comes out of the back of the stereo and is typically red.

#2. Connect the ACC wire to the ignition or cigarette lighter in your car. This will provide power to the stereo and allow you to use it.

#3. If you cannot find the ACC wire in the dash, you can connect it directly from the stereo to the battery. However, this is not recommended as you will not be able to turn the radio off while removing the key from the ignition.

#4. Once the ACC wire is connected, you should be able to use your car stereo.

Risks of Not Connecting ACC Wire to the Radio

If you do not connect the ACC wire to your car stereo, it will not work because it will not receive power.

Additionally, if you connect the ACC wire to the battery instead of the ignition, the radio will work until you turn it off on the panel because if not connected to the ignition, it will not turn off together with the rest of the car equipment if you will turn the ignition key off.

This can lead to battery drainage, and as a result, your car may not start the next time you try to use it.

Why Is an ACC Wire Important for a Car Stereo?

When installing a new car stereo, it’s important to connect the ACC wire.

As you already know, the ACC wire must transfer the signal to the stereo and tell the radio that the system is powered and allows it to turn on.

Common Problems With ACC Wires and Car Stereos

#1. A wiring issue is a most common cause of a car radio refusing to work while connected to the ignition.

This could indicate that your wires have been switched, that you need to change your wires, or that you have a blown fuse.

#2. Another common problem with ACC wires is that they can become loose over time.

This can cause the stereo to turn on and off randomly or not turn on at all.

If you suspect your ACC wire is loose, you can try tightening it or replacing it altogether, especially if there are many vibrations in the car from bad roads, for example.

#3. A faulty battery is also a common problem because there is no signal going through the ACC wire if the battery is flat.

This can happen if you leave your car stereo on for an extended time without the engine running. If this happens, you’ll need to recharge your battery before using your stereo again or replacing it.

#4. Finally, the misfunctioning of the ACC wire can be caused by a faulty ignition switch.

If the ignition is not working correctly, it can cause the ACC wire to lose or not receive power.

If you suspect that your ignition is the problem, you should have it checked by a mechanic, but with the damaged ignition switch, not only would the radio not function properly but also other accessories.


The ACC wire is an important part of a car stereo system as it provides power to the stereo. If you are installing a new car stereo, be sure to connect the ACC wire.

Additionally, if your ACC wire becomes loose or is not connected correctly, it can lead to problems with the stereo.

If your car doesn’t have an ACC wire, you can still wire the stereo to the cigarette lighter or the ignition, but if you are unfamiliar with the car’s electrical installation, it is better to leave the vehicle for the professional.