How to Find ACC (Accessory) Wire in Car

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How can I identify the ACC wire in my car?

The ACC wire is usually red and slightly smaller than the primary power line, which makes it easy to find in a car.

Your car’s ACC wire lets you use electrical accessories while the engine is turned off. If you get 0v when the vehicle is turned off, it’s most likely because the ACC isn’t set to a constant 12v. When the ignition is set on ACC or the vehicle is operating, the red wire labeled “ACC” should have power.

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However, you can only ensure this if you know how to find ACC wire in a car first. In this post, you will learn the step-by-step process for finding the ACC wire in your car so it can turn on your stereo.

How to identify ACC wire with a multimeter

Step 1: Find a Constant 12V Source

Set your multimeter to the appropriate scale, attach the ground lead to a proven good ground, then touch every wire in the speaker wire with the other lead. Make sure the ignition switch is turned off.

The constant 12V wire, often called the memory wire, can be found when the multimeter shows around 12V. In the majority of aftermarket head units, it is yellow.

Step 2: Check for the Dimmer and ACC Wires

Power on the ignition switch, crank on the headlamps, and switch up the dimmer switch, if installed, all the way after you’ve marked the 12V wire. Set the dimmer control down to recheck if two more wires are displaying about 12V.

The dimmer wire is the one that exhibits less than 12V at that juncture. Orange (with or without a white line) is the most common color for this wire.

The wire that is still showing 12v, which is generally red in color, will be the accessory wire.

When you check the wiring using the multimeter using this guide, the ACC wire will be the only one with the power.

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