How To Install A Car Stereo | Easy Guide To Replacing Head Unit

Factory car stereos can get boring pretty quickly, not to mention their low-quality audio. Having them replaced might seem tiresome, but it’s surprisingly easy to do. In fact, learning how to install a car stereo is so simple that even a beginner can do it.

The whole process takes no more than 14 steps, as shown in our guide. All you need is a few tools and some basic wiring skills, and you’re adequately equipped. Just carefully follow the steps of our guide detailed below, and you can successfully install a brand-new head unit in a little over an hour.

But first, let’s take a look at the tools you need.

What You Will Need

A couple of screwdrivers and a socket set might get you far, but they aren’t enough to get the job done efficiently and quickly. For car stereo installation, we highly recommend having all of these in your toolbox:

  • New head unit
  • Flat blade screwdriver and Phillips head screwdriver
  • Nut driver
  • Prying tool
  • Crimping tool
  • Wire strippers
  • Zip ties
  • Butt connectors (18-22 gauge pink and 14-16 gauge blue)
  • Wiring harness adapter

It should also be noted that the tools you need for stereo installation will differ from one car model to another. Sometimes, the brand for your specific vehicle may sell its own stereo installation kits, so it’s good to check with them beforehand.

Otherwise, you can always reach out to an expert about what tools you’ll need to use for your car model.

How to Replace and Install the Head Unit of Your Car — Step-By-Step

Now that you’re all set, it’s time to move on to the actual process. Here’s how to replace the head unit of your car and install a new stereo in simple steps:

Step 1 – Disconnect the Battery

Set the emergency brake and pop open the hood to disconnect the battery. With an appropriate tool, carefully disconnect the negative battery terminal. Then, tuck away the disconnected terminal so that it is away from the battery and does not accidentally reconnect to it.

You can also disconnect the positive terminal or both terminals. However, it’s risky to disconnect the positive one because the metal tool can hit other surrounding components around the battery and cause shocks, sparks, or fires. It’s more than fine to just stick to disconnect the negative terminal.

This step ensures your safety is not at risk in mishaps such as short wires, fuses, etc.

Step 2 – Pry Out the Dashboard Trim Piece

Inside your car, your stereo is fitted within the fastened dashboard trim piece. The trim piece differs from model to model. Some vehicles have a dash that goes across the width of the interior, while others have a small one that goes down to the gear shift. Regardless, both require a prying tool to remove them.

Carefully pop off the trim piece using the prying tool by pushing it into the crevices. Avoid using your fingertips for this to prevent injury. Most trim pieces will pop right out, but some have hidden screws behind plugs, ashtrays, etc. You can easily take these off using a screwdriver and then take off the trim.

Afterward, disconnect the electrical plugs that are behind the dash and leave the panel to one side.

Step 3 – Detach the Car Stereo

The stereo is held in its place by some kind of socket, Phillips heads, or screws. With an appropriate tool, carefully remove these fasteners and leave them on one side for later. Make sure all the screws are off so that the stereo comes out.

Now your factory head unit should come out with a few attachments behind it. These include the wiring harnesses, AM and FM antenna, etc. Unplug them, and your head unit should come off completely.

Step 4 – Remove the Brackets Off the Unit

Most factory radios have metal brackets on their sides which are used to fasten into the dash. These brackets should not be thrown away, as they don’t come with new head units. You should only throw them away if you’re upgrading to a larger head unit.

Carefully remove the bolts holding the bracket to the factory radio and set them aside.

Step 5 (Optional) – Use a Universal Mounting Collar

Universal mounting collars help to install stereos without additional fittings. They have metal tabs at their sides which are bent to grip the sides of the inside of a dash. This means they do not require any mounting items, like bolts, nuts, etc.

If you’re installing a smaller head unit, universal collars are perfect for the job as they can be adjusted to fit any size of stereos into your dash receptacle.

Step 6 – Check the Compatibility of the Head Unit with Vehicle

The simplest way to avoid incompatibility of the new head unit with your car is to go for a head unit that matches the existing wiring harness. But unfortunately, this will limit the number of head units that you will be able to use.

To avoid this, get an adapter harness that is fully compatible with both your head unit and car. You can also cut the harness that was originally attached to your factory stereo and attach it to your new head unit using butt connectors, crimp connectors, etc.

Options for connecting wires are in more detail in the next section.

Step 7 – Connect the Wires with the Harnesses

For this guide, we’re taking the approach of cutting the original harness and attaching it to your new head unit.

So, cut the original harness off of the factory stereo, making sure to leave about 2-3 inches of wire length from the harness. Then cut off the harness from the new head unit (in case of incompatibility). Make sure to twist the copper wires after cutting so they stay packed together.

Then, you will need to match the wires between the original harness and the new head unit according to color. So, yellow goes with yellow, blue goes with blue, and so on. Use your connectors to join the wires together.

Some receivers will have other wires that connect to different parts of the stereo, such as the green wire for the parking brake. If you have these kinds of receivers, leave the extra wires for now.

Step 8 (Optional) – Use Zip Ties to Gather the Wires

The wires on the harness and the head unit will go inside the dash receptacle. If these wires are not grouped together, they can get tangled up or collect a lot of dust.

Although it is not obligatory, you should still consider gathering these wires with zip ties so that everything is neat and nothing gets lost inside the dash.

Step 9 – Assemble the Installation Kit

The installation kit is what secures the stereo in its place while also making it look appealing. It includes a few brackets that are attached to the stereo using screws and bolts.

First, attach the side brackets to the kit and then fit the stereo into it. Once the stereo is fitted with the kit, use some screws to hold it down.

Step 10 – Plug in Additional Cables and Wires

Additional wires and cables such as USB, parking brake wires, and Bluetooth devices (microphones, chargers, etc.) should be fed through the empty dash receptacle with respective connectors facing the stereo unit. If there are many wires, consider zip-tying them as well.

Step 11 – Plug in the Head Unit

Start by plugging in the steering wheel control interface into the new head unit. Then move on to the radio harness plugs.

The radio side of the connection goes into the back of the unit. Then the antenna connectors go into the side of the unit, be careful not to pull on them too hard as they are short.

Once all the connections are plugged in, slide the head unit into the receptacle and line up the screw holes. Secure the new stereo using the factory screws.

Step 12 – Put the Dash Panel Back On

Carefully reposition the dash trim back into its original place. Make sure to secure all the possible screws and/or fasteners that hold it in place. Also, plug in the electrical plugs that you detached at the beginning of the guide.

Remember to also put back the hidden fasteners and screws behind any dials or switches.

Step 13 – Reconnect the Battery

Open the hood of your car and reconnect the negative battery terminal that was tucked to one side. Take your wrench and fasten the bolts that were previously there. Make sure they are tightly secured and that the terminal is not loose. Now close the hood.

Step 14 – Test Out the New Head Unit

Put the key into the ignition and power up your vehicle. Your new stereo should come to life. Once it has displayed the main menu screen, test it out to see if it’s working.

Play a test audio and see if the additional devices are working, such as Bluetooth microphones. These devices should instantly pair with your phone, and the audio output should be loud and clear.

Ways of Connecting Wires for a Car Stereo

Joining bare copper wires can be risky, as one wrong move can throw off the entire connection. However, there are a couple of ways to safely do this without putting your car’s internal environment in jeopardy:


This is done by using a low melting point metal alloy or solder to join the copper wires together. As a result, a permanent bond is created which cannot come undone. After the solder is done, you should also use heat-shrink tubing with a heat gun to insulate the new connection. This not only makes the wires look neater but makes them last longer and more secure as well.


This method is very fast and simple. Crimping wires with a crimping tool is easy and does not require a professional. You just need to use the correct size of crimp connector.

Among crimp connectors, there is a variety you can choose from. They include crimp caps, bullet connectors, and butt connectors, which we have used in our guide above.

Posi Connectors

They are quick and easy to use and secure wires exceptionally well. All you have to do is feed the wires through the connectors and twist the connector to secure it. Plus, they are also reusable, which other connectors aren’t.

Frequently Asked Questions

1. What are the wires attached to the head unit?

The 3 main wires include the power wires (switched power and constant power), speaker wires, and ground wires. Power wires ensure the stereo receives power from your battery, speaker wires connect the stereo to other components in the system, and ground wires cancel out unwanted noise.

2. What color wires go together in a car stereo?

The left-front speaker wires are white, the right-rear speaker wires are purple, the left-rear speaker wires are green, and the right-front speaker wires are gray. Antenna wires are blue, amplifier wires are blue with a white stripe, and ground wires are black.

If you need a visual example of this with more information, check out this video.

Also read:

3. Do subwoofers need speaker wires?

Subwoofers are required to filter out the low frequencies from speaker output since stereo amps are unable to separate them. The higher frequencies must then be redirected back to the speakers. So can use a standard speaker wire to accomplish this.

Also read:

4. What happens if you wire speakers wrong?

When you wire speakers in the wrong way, the flow of current and electrical signals flow in the opposite direction and throw off the electromagnetic field. This will not only cause distorted audio but also damage your stereo system.

Also read:

5. How much does it cost to install a head unit in a car?

It can cost around $30 to more than $100 to have your head unit installed. This depends on the model of your car, the type of stereo system, the significance of the modifications, and more.


To wrap up our guide on How to Install a Car Stereo, we’d like to advise you to be extra careful when dealing with the car battery and wiring. Take precautions before handling the battery, and read up on as much as you can about the specific wiring and harnesses for a stereo system.

With that being said, you’re all set to try this on your own. Be sure to thoroughly go through our guide one more time before you attempt it.

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