What is The Illumination Wire On A Car Stereo For?

In short, the illumination wire on a car stereo wiring harness is used to dim the screen on your aftermarket car stereo.

The wire is connected directly to your instrument cluster and provides a negative trigger or positive trigger that tells your radio when you turn on and off your headlights.

Not having a bright car stereo screen shining in the corner of your eye while you drive down a dark interstate highway could prove to be a lifesaver.

How to use the illumination wire on a car stereo

Using the illumination circuit in a vehicle is fairly simple. The first thing to do is to verify that you have a connection for that option on your factory radio harness (the harness you unplug from your factory radio).

To do that, a little trick we do is to clip on your aftermarket harness to your factory harness. After its snapped on find the orange wire with the white strip.

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Follow that wire to the factory harness and see if there is wire in that same pin location. If there is, this is a good indication that your aftermarket radio can take advantage of a factory dimming option.

Does The Illumination Wire Have To Be Connected?

The short answer is No. The illumination wire allows you to use a convenience option. It simply allows for your stereo to dim and brighten when you need it to. If this wire isn’t connected you will not lose out on any other features in the stereo or cause any issues with the vehicle’s factory side.

What Do I Hook Up the Illumination Wire To?

Aftermarket wire harnesses that are usually purchased to connect to the factory side of your car will usually have an orange wire on them.

This is usually the wire you’ll connect the orange wire that came with your aftermarket stereo to.

Alternatively, if your vehicle doesn’t have a wire for a dimmer connection at the harness behind the stereo you can use a volt meter to find which wire gets 12volts when the headlights are on.

Helpful Resources

How to Connect an Illumination Wire to an Aftermarket Radio

After you’ve verified that your vehicle has an illumination wire on the factory harness, it’s time to connect these wires.

This process is done along with the wiring of your aftermarket stereo. Connect the orange wire on the new radio harness to the orange wire with the white stripe on the aftermarket harness that clips onto your factory harness.

what happens when you short-circuit the illumination wire in Car radio?

If you short circuit the illumination wire on a car radio you will more than likely blow a fuse that is connected into the dashboard lights found in your dash.

Another thing that could stop working due to the a short circuit is the instrument cluster lights,