how to find acc wire in car

[MayaRose]

The most reliable way to find the ACC (Accessory) wire in your car is to test for a 12-volt signal at the fuse box or behind the radio that is only present when the ignition is in the "ACC" or "ON" position, and disappears when the ignition is off. You'll need a multimeter or a simple test light for this. The ACC wire is crucial for installing aftermarket electronics like a new stereo or dash cam, as it tells the device when to turn on and off with the car.

Start by consulting your vehicle's owner's manual for the fuse box diagram. Look for fuses labeled "Radio," "Cigarette Lighter," or "Accessory." The fuse box is usually located in the cabin, under the dashboard or on the driver's side kick panel. With the ignition off, use your multimeter to check for power at the fuse terminals. When you find a fuse that shows 0 volts, turn the key to the ACC position. The fuse that now shows 12 volts is your target.

Another common method is to check the wiring harness behind the factory stereo. Car manufacturers often use standard wire colors, but these are not universal. You can use a wiring diagram for your specific car model from a source like Chilton or ALLDATA.

Vehicle Manufacturer	Typical ACC Wire Color(s)	Common Location/Fuse
Honda / Acura	Red / Red with stripe	Radio fuse, Ignition fuse
Ford / Lincoln	Yellow / Green with stripe	Accessory delay fuse
Toyota / Lexus	Blue / Blue with stripe	Cigarette lighter fuse
General Motors (GM)	Brown / Orange	Ignition switch harness
Chrysler / Dodge	Red / Pink	Ignition switch or fuse box

Using a multimeter is the only surefire way. Set it to DC voltage (20V range). Connect the black lead to a known good ground (a bare metal bolt on the chassis). Probe the suspected wire with the red lead. If you get a 12V reading only in ACC/ON mode, you've found it. A test light works similarly—it will illuminate only when the ignition is on. Always disconnect the car battery before splicing into any wires to prevent short circuits. If you're unsure, seeking help from a professional installer is the safest bet.

[DiGiselle]

Grab a cheap test light from any auto parts store. It’s way easier than a multimeter. With the car off, poke the probe into one side of a fuse in the interior fuse box. No light? Turn the key to the ACC position. If the light glows, that’s the fuse for your ACC circuit. You can tap into the wire going to that fuse. The cigarette lighter fuse is a popular and easy choice for this, as it’s almost always switched with the ignition.

[LaZachary]

As a hobbyist who’s installed a few stereos, I always start by looking up a wiring diagram for my specific car model and year online. A quick search for "[Your Car Model Year] radio wiring diagram" usually turns up a color-coded chart from a site like Crutchfield. This shows you the exact wire color for the accessory wire behind the radio. But I never trust it 100%. I still double-check with a multimeter to confirm the wire loses power when the key is out. It saves you from frying something.

[MacCarson]

Safety is the number one priority. If you're not comfortable with electrical work, please consider a professional installation. Before you probe anything, always disconnect the negative terminal of your car battery. This prevents accidental short circuits that could damage your car's computer or cause a fire. When you find a wire you think is the ACC, test it thoroughly: key in, key out, start the engine. Make sure it behaves exactly as expected before making any permanent connections.