A DIY Guide to Installing a New Head Unit

How to replace a car stereo head unit with a new one

A new head unit can modernize your dashboard, improve the performance of your speaker system, and give you access to a range of media devices, such as Bluetooth control, HD and satellite radio, or even a DVD player. Installing one is a relatively easy upgrade that you may be able to do yourself, even if you're an inexperienced DIYer.

Here's how to get the job done.

Head Unit Installation Tools

To install a head unit, you'll need the right set of tools. If you haven't bought a head unit yet, make sure you get one that fits the space in your vehicle. To that end, you should understand the difference between single DIN, double DIN, and DIN-and-a-half. This will avoid headaches later on.

To complete a head unit replacement or installation, you will need the following tools and equipment:

  • Flat blade and Phillips head screwdrivers
  • Torx drivers or bits
  • Pry bar or prying tool
  • Wiring harness adapter
  • Soldering iron or crimping tool
  • If you don't have a wiring harness adapter, you will also need solder or crimp connectors.

The specific tools required to install a car radio may differ from one vehicle to the next. If something doesn't quite fit, you may need a different tool. Trying to force a square peg into a round hole, so to speak, rarely works out.

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Assess the Situation: Every Vehicle Is Different

kia rio dash and stereo head unit

Lifewire / Jeremy Laukkonen

For aesthetic reasons, the fasteners that hold car radios in place are often hidden. To access the fasteners, remove the trim piece. These trim pieces sometimes pop right out, but many have hidden screws behind the ashtray, switches, or plugs.

After you have removed the trim piece screws, insert a flat blade screwdriver or prying tool to pop off the trim piece.

Some units are held in place with other methods. Ford head units, for example, are sometimes held in by internal clasps that can only be released with a special tool.

Don't force off the trim piece, faceplate, or dash components if they will not budge. Carefully examine the area where the piece is bound, and you will probably find a screw, bolt, or other fastener holding it in place.

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Pull the Trim Back Carefully

Kio Rio dash trim with head unit of stereo pulled out

Lifewire / Jeremy Laukkonen

Once you have successfully removed all of the fasteners, you should be able to loosen and remove the trim piece. In some cases, you may need to disconnect various switches and wire connectors as well. In doing so, be careful not to yank out the wires.

Some vehicles also have climate controls connected to the head unit. If you damage these connections by pulling too forcefully, the heating, ventilation, and air-conditioning may not work properly when you reassemble the components.

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Unbolt the Car Stereo

Kia Rio radio mounting screws of stereo head unit

Lifewire / Jeremy Laukkonen 

With the head unit fasteners exposed, it's time to remove the car radio from the dash.

Some head units are held in with screws, but others use bolts, Torx fasteners, or a proprietary fastening method. (In the vehicle pictured above, the stereo is held in with four screws.) Remove the screws or fasteners, place them in a safe location, and then carefully pull the head unit free of the dash.

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Remove Any Additional Brackets

Kia Rio radio bracket on dash

Lifewire / Jeremy Laukkonen

Factory car radios are often held in place with elaborate brackets, which you may or may not need to install your new head unit.

In the vehicle pictured above, the factory stereo is connected to a large bracket that includes a storage pocket. The bracket and the space in the dash are capable of holding a larger head unit. Since, in this example, we are replacing a single-DIN head unit with a new single-DIN head unit, we will reuse both the bracket and the storage pocket. If we were installing a larger head unit, we would remove the pocket and perhaps not use the bracket at all.

If your car has such a bracket, you'll need to determine whether or not your new head unit requires it. You may be able to install a double-DIN head unit, or you may find that you have one of the few vehicles designed for a 1.5-DIN head unit.

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Install a Universal Mounting Collar, If Necessary

Kia Rio OEM bracket and aftermarket collar.

Lifewire / Jeremy Laukkonen

Most aftermarket stereos come with a universal collar that will work in a variety of applications. With metal tabs that can be bent to grip the sides of a dash receptacle, these collars can usually be installed without additional mounting hardware.

In this example, the single-DIN collar is too small to fit directly into a dash. It also doesn't fit inside the existing bracket. That means we won't be using it. Instead, we'll screw the new head unit into the existing bracket. Note that the existing screws may not be the correct size.

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Check the Plugs and Wired Connections

Kia radio plug and new stereo

Lifewire / Jeremy Laukkonen

It is easiest to install a new head unit that is compatible with the existing wiring harness. However, this limits the number of head units you can use. In the vehicle pictured above, the plug and connector do not match. There are a few different ways to deal with such a situation.

The easiest is to buy an adapter harness. If you find a harness that's designed specifically for your head unit and vehicle, you can plug it in and go. Some harnesses can be wired directly into the pigtail that came with your new head unit.

The other option is to cut off the harness that was connected to your factory radio and then wire the aftermarket pigtail directly into it. If you choose to go that route, you can use either crimp connectors or solder.

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Solder or Crimp the Wires, If No Harness Adapter Is Available

Close up of kia radio wiring

Lifewire / Jeremy Laukkonen

The fastest way to connect an aftermarket pigtail to an OE harness is with crimp connectors. Simply strip two wires, slide them into a connector, and then crimp it.

At this stage, it's vital to connect each wire properly. Some head units have wiring diagrams printed on them. Every factory head unit has its own system for speaker wire colors. In some cases, each speaker is represented by a single color, and one of the wires has a black tracer. In other cases, each pair of wires will be different shades of the same color. Aftermarket car radios use a fairly standard set of wire colors.

If you are unable to find a wiring diagram, use a test light to identify the ground and power wires. When you locate the power wires, make sure to note which one is always hot.

You can also determine the identity of each speaker wire with a 1.5v battery. You will need to touch the positive and negative battery terminals to different combinations of wires.

When you hear a slight pop of static from one of the speakers, that means you have found both of the wires that connect to it.

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Put Everything Back

finished head unit installation of stereo

Lifewire / Jeremy Laukkonen

Once you have your new car radio wired up, gently place it into the dash and turn your ignition to the accessory position. Verify that the radio works. If it doesn't, double-check your wiring job.

After you are satisfied that your new radio works, you're in the home stretch. All of the tough parts are behind you, and all you have to do is reverse the removal procedure.

In most cases, finishing the job is a matter of screwing the new head unit in place, pushing the trim piece back on, and cranking up your brand new stereo.

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