How to Wire a New Stereo in an Old Car

If you have an old car and want to install an aftermarket radio, it can be a bit challenging. Unlike modern cars, pre-made parts for classic cars are hard to find. However, with some basic knowledge, you can install a new stereo on any platform.

The first thing you need to do is to locate the best place to install the radio. If you’re lucky, your classic car may have a radio slot like the 72 K5 Blazer in the demonstration. In that case, you can put a can in the slot to mount the radio securely.

If the radio slot is not available or you want to keep the factory look, you can put the radio in the glove box, under the seat, or mount it with a universal kit underneath the dash.

Once you’ve found the best place to install the radio, you need to wire it properly. The basics of wiring a radio into a classic car are pretty simple. You need a positive wire, a ground wire, an ignition wire, and speaker wires.

The yellow wire is the constant positive wire, and you need to run it to the battery and fuse it. If you can find a constant 12-volt signal somewhere in the national ready, you don’t have to go to the battery, but make sure you’re always fused to be safe.

The ground wire can be grounded to the chassis or through the harness, and you need a solid ground with no resistance that goes to the negative on the battery. You can use a voltmeter to locate the best possible ground available.

The ignition wire is a switch signal, and you want it hot when you turn the key on into account only. Otherwise, the radio will be on all the time and drain the battery, causing issues down the road. Find a 12-volt switch source that’s hot only when the key is on and connect it to the ignition wire.

If you have an amplifier or an aftermarket something else added within the vehicle, you need to connect it to the amplifier wire.

The speaker wires are different for every car. For example, the 72 K5 Blazer has supply lines in the doors, and the previous installer had run speaker wire from those doors up through the dash. If you don’t have an amplifier or anything else, you would use the speaker wires from the radio.

There’s no wiring harness adapter available for classic cars, so you need to wire everything manually and make sure the connections are solid and clean.

In the demonstration, the previous installer had put a pioneer radio in the 72 K5 Blazer, and they replaced it with a new one with Bluetooth. They only used the front two speakers and connected them to an amplifier that would push the two interior speakers.

After locating the positive, negative, ignition, amplifier, and speaker wires, they plugged the main wiring harness, antenna, Bluetooth blank, and RCA cables into the new radio and did a quick test to make sure everything worked.

If you have any questions about how to install an aftermarket radio on a classic car, please post a comment below. Keep in mind that this is a universal video, and every classic car can be different.


Can you put a new stereo in an older car?
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Can you put a touch screen radio in an older car?
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Do I need a wiring harness to install a car stereo?
Whether you're installing a new stereo, swapping out your air conditioner compressor, or just replacing a set of speakers, you'll likely find yourself in need of a wiring harness. These simple devices make it easier to connect new electrical components to the factory-installed wiring in your car.