Windupradio is supported by its audience. When you purchase via our links, we may get a commission. Learn more

How to Install a Radio Without a Wiring Harness Adapter?

Writen by Edwin Jones

Fact checked by Andrew Wright

how to install a radio without a wiring harness adapter

Installing a factory radio in your car is an easy but intimidating task, especially for those who are inexperienced. Most of the time, the radio will come with everything you will need. But what if it does not include a harness?

To wire a car stereo without a harness, start by knowing the purpose of each wire or where it connects. Next, turn off the power supply. Strip the wires at least half an inch and connect them to the right pair. Alternatively, you can use a make-shift harness using a rectangular header connector.

Read on as I share how to install a radio without a wiring harness adapter. It can be a bit tricky if you do not have the knowledge, but after reading this guide, you will realize it is easy.

What You Will Need to Follow this Tutorial

Before I talk about the specifics of how you can wire a radio without harness, here is a quick rundown of the materials you will need:

  • Radio
  • Wires
  • Wire stripper

A Step-by-Step to Install a Radio Without a Wiring Harness Adapter


Ready to start? Follow the steps I will briefly talk about below:

Step 1. Understand the Wires

Assuming that you are done unboxing the radio, the first thing to do is to understand the wires. There are wires of different colors, each designed for a specific purpose. By knowing what each wire or color means, you can easily put them in their respective positions.

The yellow power cable is for connecting the unit to the battery. It is the wire that provides a stable power supply. Meanwhile, the red wire is for turning the radio on and off. The black, wire, on the other hand, is for grounding the radio.

  • Power Cables

As the name implies, these wires are responsible for power transmission, which is what will make the radio and other components work.

  • Speaker Wires

Most aftermarket radios will include one pair of speaker wires. The negative terminal wires are stripped while the positive terminal wires are unstripped.

As for the color, the gray wires connect to the right front speaker while the white wires connect to the left front speaker. For the rear speakers, purple is for the right side while green is for the left side.

  • Brightness Wires

The set-up will also include wires that are used for adjusting the brightness on the face of the radio. They are both orange. One wire is for increasing brightness while the other wire is for decreasing brightness. However, not all radios will have these wires, especially if you are using an older model.

  • Antenna Wires

To improve the performance of your car radio, even in difficult environments, you will need an antenna. The antenna has to be connected to the radio with a wire. To connect to AM and FM frequencies, you will need a pure blue wire. If it has stripes, you can use it for connecting to Bluetooth.

Step 2. Cut the Power

Now that you are familiar with the different wires and their uses, it’s time to start. The first step is to cut the power supply. Turn off the ignition and disconnect the battery or the power supply. This is important as it will minimize the possibility of electrocution and let you work safely.

Step 3. Strip the Wires

As you wire a radio into a car without a harness adapter, you will need to strip the cables yourself. Without proper insulation, the wires will be easily prone to wear, and hence, they can break within a short time of use. Strip only a few inches.

Step 4. Connect the Wires

After stripping the wires, now is the time to connect them. This is confusing, especially if you have not done it before. I suggest that you go online and look for how to install a car stereo system wiring diagram. This will serve as your guide, making your life easy.

When connecting the wires, see to it that you do it in pairs. For instance, the red wire should connect only to the red wire on your car.

Depending on your car, you will find two types of wiring setup.

The first has a bunch of cables without a harness. If this is the case, find the matching colors and connect them to each other. You should solder and heat shrink the wires after connecting to establish a strong bond between the two.

You will also encounter a set-up with only a single wire. It has a positive and negative head. Just match the cables and you will be done with the connection.

Pro Tips


Aside from the things mentioned above, here are some tips that will help in completing the task like a pro.

1. Make Your Own Harness

Instead of manually stripping and connecting the wires, there is another alternative worth considering – make a harness. You can do this by using a rectangular connector unit, which is what will link the wires to the power supply of your vehicle.

Look for a rectangular header connector with a through-hole mount and a female-type socket. While it is more commonly used for a circuit board installation, you can also use it as a make-shift wiring harness.

For the new connector, spacing is important. The number of pins, on the other hand, is not as crucial. You can use smaller connectors if you need more pins.

With the rectangular header connector ready, you will need to solder wires on the pins. You should also heat shrink the wires, which will help keep them strong even after years of use and exposure to harsh elements that can speed up wear.

2. Mind the Colors

Working with multiple wires can be confusing, especially if you are not a handyman. Go online and look for car stereo wires color code. This will give you an idea on which wire is for which purpose. It will prevent you from wasting time and effort since you are assured that the wires will connect correctly.

3. Solder Wires Like a Pro

One thing that most people might find intimidating in the steps mentioned above is soldering the wires. You will need the right soldering iron. Look for one that is lightweight and compact so you can hold it comfortably and easily.

Be mindful as well of the tip of the soldering iron. This will depend on the size of the wires you are dealing with. Wider wires will require wider tips.


Wiring a radio without a harness may seem like a difficult task at first, but with the right knowledge and a bit of time, it is easy work. It requires a basic understanding of the kind of wires. Next, you will need to cut the power, strip the wires, and connect them to their right pair.

Did you like this article on how to install a radio without a wiring harness adapter? Is there anything else that you would like to add? Do not hesitate to leave a comment below.

Read more: How much money to install a car radio?

5/5 - (5 votes)