How To Install a Car Stereo | O'Reilly Auto Parts

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These steps will cover how to wire a stereo with or without an adapter kit, as well as simple speaker installation. You’ll need to make sure that the stereo you’ve purchased fits the space you have to install it in, and determine whether or not an adapter kit is available for your vehicle. If you’re not completely comfortable doing this yourself, we’d be happy to recommend a professional technician in your area.

Disconnect the Negative Battery Cable

Step 1: Disconnect the Negative Battery Cable

The first step to any car stereo installation is to disconnect the negative battery cable.

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Remove Any Trim or Hardware

Step 2: Remove Any Trim or Hardware

Depending on your vehicle, removing the old stereo may require removing hardware, adjacent components or interior trim. In other cases, you may just need a screwdriver, trim tool, socket or specialty stereo removal tool that slides into the holes in the face of the stereo and uses loops to work the stereo out.

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Disconnect Wiring Harnesses

Step 3: Disconnect Wiring Harnesses

Once it’s out of the dash, you’ll need to disconnect the wiring harness or harnesses, as well as the antenna, from the back of the stereo.

Do It Right: Make sure nothing else needs to be removed before installing your dash kit.

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Install the Dash Kit

Step 4: Install the Dash Kit

Many dash kits simply snap into place, but be sure to follow the instructions for your specific kit.

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Most newer vehicles will have an adapter kit available to make installation simpler. If you were unable to find a suitable adapter kit, or you’re dealing with missing or damaged wires, see Instructions for Hard-Wiring Installation below.

Understand the Adapter Kit

Step 5: Understand the Adapter Kit

Most adapters will have a connector on one end that connects to your vehicle’s existing wiring harness. Some adapters may also have the correct connector at the other end for the new stereo. If that’s the case, you can simply plug the adapter into the wiring harness in the vehicle, plug the other end into your new head unit, and reinstall the antenna wire. Skip to Install the Head Unit.

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Secure the Wire Connections

Step 6: Secure the Wire Connections

If the adapter has no connector on the stereo end, follow the instructions for your adapter and your new stereo to determine which wires need to be spliced together. Use wire strippers to bare the end of each wire, twist the ends of the wires together, and use wire crimpers and butt connectors to secure the splices.

Do It Right: Test the wire connections to make sure they’re secure. If a wire pulls out or seems loose, cut the connector off, strip the wire again, and use a new connector to secure that connection.

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Protect the Wire Connections

Step 7: Protect the Wire Connections

If you used butt connectors with heat shrink, use a heat gun to shrink the end of the connector over the wire itself. If you chose to use open-ended butt connectors, it may be a good idea to wrap the connections in electrical tape, or use individual pieces of heat shrink over each connector.

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Step 8: Install the Head Unit

Step 8: Install the Head Unit

Once the adapter is secured at both ends with any wiring that needs to be done, reconnect the antenna and install the head unit in the dash.

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On many vehicles, especially older vehicles or applications where a radio was not previously installed, hard-wiring your new stereo system may be necessary or preferred. This may be somewhat more involved than simply plugging into an adapter, but can yield the same results if appropriate steps are followed. You may need to tap into wires under your dash or run completely new wires if:

Your vehicle is older
Wiring has been removed
Wiring has been damaged
The vehicle has never had a stereo
You’re unable to find a suitable adapter kit

Before doing anything else, you’ll need to find a source of continuous power, a source of accessory power, and a ground wire, preferably from a wiring diagram for your vehicle. If you have a diagram, skip to Connect & Secure Power Source & Ground Wires. If you don’t have a diagram, you can use a test light or multimeter. (Reconnect your negative battery cable before probing for power and ground.)

Find Power Sources

Step 9: Find Power Sources

If you’re using a test light, you’ll see it light up when the probe contacts a power source. If you’re using a multimeter, you’ll use both the ground and the power probe to get a voltage reading. You’ll need to find a source of continuous power that has 12 volts whether or not the key is turned, and a source of accessory power that has 12 volts only when the key is in the “run” or “on” position.

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Find or Add a Ground Wire

Step 10: Find or Add a Ground Wire

Ground wires are typically black, but if you can’t locate one that’s usable, you can add one yourself using a wire, ring connector, and self-tapping screw. Once power and ground wires are determined, be sure to disconnect the negative battery cable.

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Connect and Secure Power Source and Ground Wires

Step 11: Connect and Secure Power Source and Ground Wires

Use wire strippers to bare the end of each wire, twist the ends of the wires, and use wire crimpers and butt connectors to secure the splices, making sure the connections are secure. Dress the wires with electrical tape before tucking them into the dash.

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Connect the Remaining Wires

Step 12: Connect the Remaining Wires

A typical new stereo may include the following wires:

Eight speaker wires (a positive and a negative for four speakers)
Power antenna control
Illumination or backlight
Amplifier remote turn-on
Steering wheel/external stereo controls

Your system may not include all of these accessories. Simply cap or tape the ends of the wires you don’t need to keep them from shorting out.

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Connect the Radio Antenna

Step 13: Connect the Radio Antenna

Once you’ve connected your continuous and accessory power sources and ground wire, it’s time to connect the radio antenna. Some antenna connectors are universal, but some require an adapter for connection.

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Secure All Other Accessories

Step 14: Secure All Other Accessories

If your new stereo came with a microphone or other accessories, ensure they're installed securely and tucked behind trim panels or secured with cable ties wherever possible.

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Connect Accessories

Step 15: Connect Accessories

You can then connect any accessories, including microphones, amplifiers, or accessory connections, and any other auxiliary components, to the rear of the head unit.

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Install the Head Unit

Step 16: Install the Head Unit

Slide the new stereo into place in the dash and secure it with the necessary hardware.

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Reconnect the battery, then turn on the key to test your new car stereo, making sure it works when the key is turned to the “run” or “on” position.

Troubleshooting

Step 17: Troubleshooting

If the stereo doesn’t come on or isn’t making noise when it does:

Make sure the fuse is intact
Check the continuous power connection
Check the accessory power connection
Check the ground wire connection

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Test Power Sources

Step 18: Test Power Sources

You should also turn your vehicle off to ensure the radio turns off automatically, and turn it back on to ensure it’s saving any presets.

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Finally, if you’re wiring new speakers to complete your stereo upgrade, you can do it in one of two ways, including using speaker plug adapters or installing new terminals to new or existing wiring.

Remove Panels & Trim

Step 19: Remove Panels & Trim

Start by removing any panels and/or trim to allow yourself access to the speaker housing.

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Installing Speakers With Adapters

Step 20: Installing Speakers With Adapters

If adapters are available and you’re reusing the factory speaker harness, it may be as simple as plugging in the adapter and then connecting the speaker terminals at the other end. Then mount your speaker in the door or package tray and reassemble any trim that was removed.

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Installing Speakers Without Adapters

Step 21: Installing Speakers Without Adapters

If you’re running new speaker wires, no adapter is available, or your factory plug is damaged, identify your positive and negative speaker wires and the corresponding terminals on the back of the speaker. Then choose the appropriate crimp connector, strip the speaker wires, and crimp the connector into place.

Do It Right: Make sure you use the proper connector on the appropriate wire to be certain the speaker receives the necessary signal.

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Reinstall Trim and Test the System

Step 22: Reinstall Trim and Test the System

Once you’ve tested your new speakers and stereo, you should be ready to reassemble any other trim or panels you removed.

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The automotive repair work depicted in this series is performed under the direction of the manufacturer of the product featured. Prior to undertaking any of the demonstrated repairs on your vehicle, we suggest you consult with a certified mechanic or another professional who can adequately advise you of the proper repair or remedy required. O’Reilly Automotive Stores, Inc. and its affiliates (“O’Reilly”) disclaims any responsibility for injury or damage resulting from a viewer’s attempt to recreate the repairs shown in this series.