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HomeTips & GuidesMake Your Own Car Radio Wire Harness: An Ultimate Guide on Building Car Radio Wire Harnesses.

Make Your Own Car Radio Wire Harness: An Ultimate Guide on Building Car Radio Wire Harnesses.

Make Your Own Car Radio Wire Harness: When you install a new stereo in your car, you may have to do some modifications.

These modifications become more critical when your new stereo harness is incompatible with the existing stereo harness in your car.

But how will you customize your car radio wire harness? Let’s find out this in detail in the following writeup.

Table of Contents

What is a car stereo harness?

You may know the stereo harness by different names like stereo wiring harness, stereo wiring assembly, or stereo wiring loom. 

The harness joins all the electrical wires and cables to carry an electrical signal/power from the car’s main supply to the designated accessory or system.

All harness wires connect through non-conductive materials such as electrical tape, rubber, or vinyl. 

Both ends of the harness have a plastic device called a connector/terminal. These connectors act as pull-push switches when a device connects to its corresponding part.

These connectors are either male or female connectors. 

If there is a male connector, you must insert it into the connection point, while the female connector will receive the male connector at the connection point. 

You must have noticed such a connection in audio and video cables.

A car’s stereo wire harness has a standard structure, but even then, you will see that not all car stereos have the same harness. 

The design and number of wires are the same but may differ visually.

Advantages of the car radio wire harness:

A stereo harness, more or less like an adapter, helps you install a market-bought stereo inside your car with certain benefits.

Lesser installation time:

Each vehicle requires a complicated web of wires that connect all the systems and accessories to function normally. 

Installing meters of wires in the car can be pretty daunting. However, a stereo harness simplifies the wiring connection by putting all the wires into a single terminal.

Although aftermarket stereos have the same inputs and outputs as the stock stereo, the location of these inputs and outputs is not the same. 

Using a car stereo harness adapter simplifies this installation process. 

Connect one end to the stereo and the other to the original wiring harness, which was earlier connected to the factory-fitted stereo. 

Safe and secure:

In a harness, all wires connect firmly at the end terminal. As a result, the individual wires are less prone to damage by vibration, general wear and tear, and elements. 

Setting up a harness also optimizes a vehicle’s space.

Additionally, as all wires have one terminal fixed, there are fewer chances of short circuits.

Lastly, the structure and formation of a harness reduce the risk of electrical fires in the vehicle.

How to make your car radio wire harness?

Suppose you want to change the factory-fitted stereo of your car. You may not need any radio harness as aftermarket stereos come with the wiring harness.  

If you have possessed an aftermarket stereo already, you may need a specialized harness.

Here are the steps to make a new car stereo wire harness from scratch:

Cut the vehicle’s harness and new stereo harness.

You can build a new harness from your vehicle’s existing harness. For this, you need to cut the harness at the proper length. Also, cut the stereo harness to an appropriate size. 

If you find any of the two harnesses too short, you can use stereo wires in between to complete the length.

Refer to the vehicle-specific diagram and stereo model:

A vehicle’s stereo wiring diagram is a graphical image of all the wires’ locations and their connection to their terminals. 

This image shows a table/list correlating with the graph’s wires and connection. 

Use this diagram to know which wire will go at what point and route all the wires accordingly.

Radio pigtail wiring harness

Radio pigtail wiring harness

Find necessary wires:

The wiring diagram shows you wires of different colors. Each color wire has its specific purpose. Follow the wiring diagram to understand each wire color and its role.

For instance,

  • The yellow wire connects directly to the battery. You can also call it a constant wire, as this wire constantly supplies power to the car stereo. It also acts as a memory backup as it saves all the presetting of the stereo when you turn your stereo ON/OFF.
  • The blue wire is for the power antenna or remote turn-on. Suppose you have an amplifier with a distant connection point; this blue wire will connect to that amplifier. Thus, the amplifier connects automatically whenever you switch on your car’s stereo.
  • There are green wire leads for rear right speakers, wherein solid green indicates positive wire, while green-black is for negative one.
  • Purple wire leads are for rear right speakers, wherein solid purple is for positive wire while purple black is for negative.
  • The front speakers (right) have gray wires with solid gray for positive and black for negative.
  • For the left front speaker, there are white wires. Here also, the solid one is for positive wire. And the white black is for negative wire.
  • Then, there is a black wire meant for grounding. The wire connects to the car’s metal part or to the battery’s negative terminal. The grounding by the black wire reduces noise interferences of the stereo.
  • The red or trigger wire turns on the stereo when you insert and twist the key to the ignition point.
  • Lastly, there is an orange wire, which is an illumination wire. In some stereo, you will find orange-black wire, which has the same function as this illumination wire but works as a dimmer wire. The illumination wire helps you adjust lights coming from the stereo.

Connecting wires:

First, strip the insulation and connect harness wires to the stereo wires based on the color codes given in the wiring diagram.

Most people use a pair of scissors to strip the insulation. Then, they twist the two ends together and cover the connection with an electrical tape. 

However, there are better ways to connect wires than this, as you lose the wires or increase the chances of short circuits with this method. 

Further, the electrical tape you use to cover the connections may loosen over time due to vehicle vibrations. 

Thus, the preferred choice for removing insulation is through wire strippers. 

These strippers are designed to remove insulation from the wires and not damage the internal wires and conductors. 

After removing insulation, the best way to join wires is through soldering. Many people crimp wires to join them, which is also not advisable. 

Soldering of wires creates a permanent connection that is resistant to all types of wear and tear and vibrations.

Finally, sealing the soldered connections through shrink is essential as this is more effective and long-lasting than electrical tapes.


The need for making a vehicle wire harness can arise at any time. If you are looking for customized wiring harness solutions, Cloom is the one-stop solution. 

We have all sorts of wire harnesses and cable assemblies for vehicles and other electronics. We can also make custom designs as per your requirements. 

Contact us, and please discuss your requirements.

I am Lillian Yang, having been a sales manager for over 10 years.

I have received many positive reviews from customers. They have praised our excellent service, on-time delivery, and high-quality cable assemblies.

For your projects, please provide cable assembly files/images/smples, etc., so that I can send you a quotation within 24 hours.

Contact me now and let’s get started on building your wire harnesses!

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