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How to wire a Car Stereo without Wiring Harness
How to wire a Car Stereo without Wiring Harness?

If you’re installing a new car stereo, and don’t want to use the factory wiring harness, you’ll need to know how to wire it yourself. 

Wiring harnesses make the process much simpler by providing all the necessary connectors and wires for your new stereo. But if you don’t have a wiring harness, don’t worry – it’s still possible to install your new stereo yourself.

This guide will show you how to wire a car stereo without a harness in seven easy steps. Just make sure you have the right tools and connectors, and you’re good to go!

Keep in mind that depending on your car’s make and model, the process may vary slightly. However, in general, the steps are pretty similar no matter what kind of car you have.

How to wire a car stereo without a wiring harness adapter

There are a few reasons why you might want to wire a car stereo without using a harness. Maybe you’re installing a new stereo in an older car that didn’t come with a factory stereo, or maybe you’re upgrading your car’s sound system and want to add some amplifiers or other accessories. Whatever the reason, it’s not as difficult as it might seem. Please Follow the below step to install car stereo with using wiring harness adapter

Remove The Old Stereo

In order to install your new stereo, you’ll first need to remove the old one. This process will vary depending on your car, but it’s usually pretty straightforward. There are usually a few screws holding the stereo in place, so remove them and pull the stereo out. You may need a wire hanger or other tool to release the stereo from its mounting bracket.

Tools and Materials Needed:

  • Wire Stripper
  • Crimping Tool
  • Circuit Tester
  • Crimp Cap
  • Electrical Tape

Identifying Car Stereo Wiring harness

  • Yellow Wire – Constant
  • Blue Wire- Remote turn on 12V and Power Antenna 12V
  • Black Wire – Ground 
  • Red Wire – Accessory 12V
  • Orange Wire – Illumination
  • Orange Black Wire – Dimmer
  • Green Wire – Left rear speaker Positive
  • Green Black Wire – Left rear speaker Negative
  • Purple Wire – Right rear speaker Positive
  • Purple Black Wire – Right rear speaker Negative
  • White Wire – Left front speaker Positive
  • White Black Wire – Left front speaker Negative
  • Gray Wire – Right front speaker Positive
  • Gray Black Wire – Right front speaker Negative

Now you know the basics of car stereo wiring, let’s move on to the installation.

How to Identifying Car Wiring and Connect it to a Car Stereo Wiring Harness

Constant wire in a car

First, strip the wire about half an inch. After that, use a Circuit Tester and touch each of the wires until it lights up. The test light not lighting up usually means that the constant wire goes directly to the battery.

Be careful not to let the wires touch each other as it could short out the wire. If there is no power on any of the wires, check the fuse to see if it is blown. The dome light and the radio are usually connected to the constant wire.

Once the constant wire is found, twist it with the yellow wire on the car stereo wiring harness. Then put a white cap on it and use a high-quality crimp tool to connect the two wires.

Ignition switch for accessory wire:

You will need to take your key and put it in the ignition. Then, turn it to the on position without starting the car. Now, you will need to find the ignition switch for the accessory wire.

To do this, you will need to take your Circuit Tester and touch each one of the wires with the test light until it lights up. 

Once you have found the wire that lights up, twist it together with the accessory wire you found on the Car stereo.

Then, go ahead and twist those two wires together and put a white cap on it. Use a high-quality crimp tool to connect the two wires. This will ensure a good connection.

Illumination wire:

First, you need to identify the illumination wire on the car. The wire will usually be brown, but it may also be white or another color. To find it, turn on the headlights and use a circuit tester to touch each wire in the harness until the test light illuminates.

Once you have found the illumination wire, twist it together with the orange wire from the Car stereo harness. Then, use a high-quality crimp tool to connect the two wires. Finally, put a white butt connector on the connection.

Ground wire:

First, take the wire and stick it into the constant power on the radio wiring harness. Second, take the end of the test light and hook it to the end of the wire that’s been jammed into the constant wire. Third, touch the test light to different wires until you find the one that lights up, which indicates that it’s the ground wire. Black wires are typically used for ground on cars.

Speaker wire

You can use this method to identify the speaker wires if you have a nine-volt battery and alligator clips. Simply connect the alligator clips to the battery, with the negative on the negative and the positive on the positive. 

Then, touch the wires together and listen for a pop sound. This will help you to determine which wires are inside the vehicle. If you touch the wires together and the speaker moves out, you correctly connect the positive and negative. If the speaker moves in, you have the wires reversed and need to adjust accordingly.

Then, twist the stereo speaker wires and car wires together and put a white cap on it. Use a high-quality crimp tool to connect the two wires. This will ensure a good connection.

To find the other speaker wires, follow this method for the positive and negative wires.

Install your new car stereo

Install your new car stereo

Once all of the connections have been made, you can now install your new stereo. Start by gently pushing the stereo into the dash until it clicks securely into place. Then, secure the trim pieces and any other obstacles that were removed earlier.

Test your new stereo

Before you put everything back together, it is important to test your new stereo to make sure it is working properly. Start by turning on the vehicle’s ignition and then turn on the stereo. If everything is working correctly, you should see the display screen turn on and be able to control the volume and other functions.

If you do encounter any problems, double-check your wiring and connections to make sure everything is connected properly. Then, try testing the stereo again.

Once you are confident that your new stereo is working properly, you can put everything back together in reverse order and enjoy your brand new car audio system!​

Troubleshooting tips.

If you’re having trouble getting your car stereo to work after wiring it without a harness, here are a few troubleshooting tips:

Make sure all of your speakers are connected properly. Consult your car’s stereo wiring diagram for help with this.

If you’re using an aftermarket stereo, make sure it’s compatible with your car. Some stereos require special adapters or harnesses for installation.

Double check all of your connections and make sure they’re tight. Loose connections can cause problems.

How can you make a wiring harness for a car stereo?

Making a wiring harness for a car stereo is not as difficult as it may seem. With the right tools and materials, it is relatively easy to do. The most important thing is to have patience and be careful when working with the wires.

The first step is to gather all of the necessary tools and materials. You will need a wire stripper, a wire cutter, a soldering iron, and some electrical tape. You will also need the stereo itself and the car’s wiring diagram.

Once you have all of the tools and materials, you can begin to work on the harness. First, you will need to find the positive and negative wires on the stereo. These are usually color-coded, so it should not be too difficult to find them. Once you have located the wires, you will need to use the wire stripper to strip away a small section of the insulation.

Next, you will need to solder the wires to the stereo. Be sure to use a strong soldering joint so that the connection is secure. Once the wires are soldered to the stereo, you can then use electrical tape to insulate them.

Finally, you will need to test the wiring harness to make sure that it is working properly. To do this, simply turn on the stereo and see if there is sound coming from it. If there is no sound, then you may need to check the connections to make sure that they are secure. If the harness is working properly, then you can now install it in your car.

With the right tools and materials, making a wiring harness for a car stereo is not as difficult as it may seem. With patience and careful work, you can easily create a harness that will provide years of use.


Wiring a car stereo without a harness may seem like a daunting task, but it’s actually pretty simple. With a little patience and effort, you can easily do it yourself. Just be sure to disconnect your battery, consult your car’s stereo wiring diagram, and test the speakers before putting everything back together. Good luck!

FAQ’s: How to wire a Car Stereo without Wiring Harness

What color are rear speaker wires?

Rear speaker wires are usually either blue or red. If your car stereo has two sets of rear speakers, one set may be blue and the other may be red. In most cases, the right rear speaker will be blue and the left rear speaker will be red. You’ll need to match up the colors of the wires in order to connect them properly.

What is a SWC connector?

A SWC connector is a type of electrical connector used to connect two wires together. SWC connectors are also known as solderless wire connectors or quick-connect terminals. SWC connectors are typically made from copper or brass and have a plated finish that helps to prevent corrosion. SWC connectors are available in a variety of sizes and styles to accommodate different wire gauges and applications.

Which side is positive for a speaker?

The positive side of a speaker is the one that has the red wire. The red wire is typically connected to the + terminal on a speaker, while the black wire is connected to the – terminal. If you are using a powered speaker, then the red wire will be connected to the positive terminal on the amplifier and the black wire will be

What happens if you mix up positive and negative speaker wires?

If you connect the positive wire to the negative terminal and the negative wire to the positive terminal, then the speaker will not work. The electrical current will flow in the wrong direction and the speaker will not be able to produce sound.

What does A and B mean on speakers??

A and B refer to the left and right channels on a speaker. Most speakers have two channels, which allows them to produce stereo sound. The A channel is the left channel and the B channel is the right channel. If you are using a mono speaker, then it will only have one channel.

What color is positive and negative speaker wire??

Positive speaker wire is typically red, while negative speaker wire is typically black. However, it is important to check your specific stereo system’s wiring diagram to be sure. Incorrectly connecting positive and negative wires can damage your speakers or cause other problems.

What happens if car speakers are wired backwards?

If your car speakers are wired backwards, the sound quality will be diminished and the speakers may not work properly. Additionally, if you wire your car stereo system incorrectly, you could cause damage to your car’s electrical system. Always consult a professional when installing a car stereo system to ensure proper installation.

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I'm Miles Walker and I'm the founder of I've been in the car audio industry for over 20 years and have a wealth of knowledge to offer on all things related to car audio. I graduated from UC Berkeley with an electrical engineering degree, so you can rely on me for top-notch expertise and advice when it comes to upgrading your sound system.

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2 thoughts on “How to wire a Car Stereo without Wiring Harness Adapter”

  1. thank u that was very helpful I’m installing a pioneer in my 96 Ford mustang and now I know why the last stereo didn’t keep the display settings but it was also a more complex stereo that didn’t have all the software to run it so im go simpler again thank u i like DIY videos


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