Car Speakers

How To Find Ignition Wire For Stereo?

Mike Cross
Updated Oct 18, 2020
How To Find Ignition Wire For Stereo

Finding a particular wire when doing electrical things can be a challenge. This is especially true if you are new to wiring things. It could be anything from wiring in a house to a car stereo, that finding the right wire can be hard. Well, in this article we are going to focus on the later and that is your car stereo. After reading this article you will be able to locate your radios ignition wire. You will also learn what some of the other wires go to in the process of learning how to find the ignition wire. Read on to learn all the tips you need to locate your stereo’s ignition wire in your vehicle.


The first way to locate your vehicles stereo ignition wire is to find a diagram of the wiring for your car. It is key though to find the exact make, model, and year diagram because some manufacturers change small things such as the wiring from year to year.

If you can locate a diagram of the wiring, then all you have to do is look at it and read it. Then match up what you see on the picture with what you see in the car. It really is that simple. However, coming across a diagram may not be that easy. Even with the internet some information and diagrams can still be hard to find. This is especially true if you have an older vehicle. Not all diagrams are able to be obtained.

How To Find Ignition Wire For Stereo?

Also, another thing to remember with using a diagram to locate the ignition wire to your radio is that diagrams only work with a car that is still factory. What if you bought the car from someone else and they changed the radio? You could try to find a diagram for the new stereo that is currently in the vehicle, but this isn’t always possible either.

Luckily for you, there is a way to locate the ignition wire in a vehicle without having a diagram. It is really pretty simple to do. It may seem complicated at first because of all the different wires coming out of the stereo, but after reading this guide you should be able to do it at home yourself

Tools you need

The tools needed to test the different wires coming from your stereo aren’t too many. All you need is a multimeter or test lamp.

A multimeter works better than a test lamp, but if all you have is a test lamp, then you can use that. If you need to find Best Automotive Multimeters, let find it on the Autofthing website, it list top 5.

The first thing to do is to get the radio out of the housing so you can get to the wires in the back. This should be common sense, but for some, it isn’t. You then have to find a good ground for the multimeter and connect on the clamp to it.

After you do that it is time to start testing wires.

How to test wires

Most radios will have a handful of wires coming out of them which you already know because you should have the stereo to a point where you can see the wires. They are all different colors and most of the time the colors can help tell you what they are. This isn’t always the case though, especially if you are working on a vehicle with an aftermarket radio installed into it. Normally the black wire coming from the radio is the ground wire. The yellow wire coming from the radio is the constant power wire. There is also probably a red wire and that is normally the ignition wire. To make sure that is the case though we have to test the wires. You also might have to test because there might be two red wires where one is the ignition wire and other is the dimmer wire.

Stereos in cars normally have constant power going to them even when the car is off. That is how it stores the presets in memory and some will display the time. To find the constant power wire you just have to take the multimeter and touch each wire with the probe that is not grounded with the car off. The one that gives a reading of 12 volts with the car off is the constant power. You can use tape and label it, especially if it is not the yellow one.

That leaves a couple of other wires for you to test to find the ignition wire. To locate it start the car and make sure the headlights and dimmer is all the way up. Use the probe and see that both potential other wires read 12 volts or more. Then lower the dimmer and see which one the reading changed on. The one that the reading changed on is the dimmer wire if your stereo has that and the other is the ignition wire. Label them so you don’t lose them.

Once you have located the ignition wire, the ground wire, the constant power wire, and the dimmer wire, you now know that all the rest of the wires go to different speakers. They normally are multicolor such as green and black. If the red wires aren’t power wires, then you will just have to check the others until you are getting ones with 12-volt readings.


Finding your stereo’s ignition wire really is that simple. There are two methods to find it. One is you can find a diagram of the car’s wiring and match the wires up. It is a key tip to remember though that the year, make, and model of the diagram need to match the car exactly, or else it might not match up. The other method is to use a multimeter and test the wires.

Using a multimeter is an easy way to find the ignition wire and sometimes it might be easier than locating a diagram. Also, it is the only method that is guaranteed to work with an aftermarket stereo. One last tip to remember is that wires are normally color coded and the red one is normally the ignition wire. That isn’t always the case though, so that is why it is a good idea to test the wires. Luckily, for you after reading this you now know the tips and tricks to locate your radio ignition wire.

Mike Cross
Life is too short to drive with stock audio

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