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HomeTips & GuidesCar Stereo Wire Harness ACC Output: How to Identify Stereo Power Wire

Car Stereo Wire Harness ACC Output: How to Identify Stereo Power Wire

About Car Stereo Wire Harness ACC Output: Buying a new wiring harness for your brand-new stereo system must provide standard connectors and wires with proper color coding. All these wires and connectors must match the original wiring of the vehicle and the new stereo.

While connecting a new stereo wiring harness, connect one end to the new stereo and the other to the vehicle’s existing wiring. With this simple plug-and-play design, there are minimal chances of errors while connecting wires. 

A stereo wiring harness has speaker wires, ground wire, power, and other connections to control the steering wheel or to integrate a fitted amplifier.

Among the different types of wires used in car stereo installation, one is a 12V accessory wire. Let’s know about this car stereo’s wire harness acc output wire.

Table of Contents

Colored stereo wires and their respective connections

Yellow 12V memory
Red 12V ignition
Orange Dash light
Black Chassis ground
Blue Antenna 
whiteLeft front speaker (positive)
White with black stripesLeft front negative (negative)
Green Left rear speaker (positive)
Green with black stripesLeft rear speaker (negative)
Gray Right front speaker (positive)
Gray with black stripesRight front speaker (negative)
VioletRight rear speaker (positive)
Violet with black stripesRight rear speaker (negative)

Which wire powers a car’s stereo system?

Some cars have two wires to power their stereo system, while others have three.

  • One is a 12-volt constant wire in yellow wire color. It is named so because it works whether the car’s ignition is ON or OFF, and for the same reason, it is always hot. It gives power to the clock presets.
  • The other one is a 12-volt acc wire in red color. Acc stands for accessory, and this wire turns on the car’s stereo when you turn the ignition ON and START.
  • The last one is an illumination wire in orange and white strips. Also known as the dimmer wire, it powers the vehicle’s dash lights and headlights. These lights become dimmer or shinier due to this wire only.
Start system

Start system

Further, understand car stereo wire harness ACC output

The 12V acc wire runs from the car’s stereo to the ignition switch’s acc wire. Thus, as you switch on the ignition, the wire gets activated and switches on the stereo. 

If the connection of the 12V wire breaks from the ignition switch, your car’s stereo may not start.

Now, as soon as you take your key out, the acc wire loses its power, thus drawing back power from the stereo. As a result, your stereo turns off automatically.

The car stereo wire harness is attached 

The car stereo wire harness is attached 

How can you identify car stereo wire harness ACC output?

Though the red color makes it easy to identify this 12V acc wire, there is another simple way to find it among the tangled web of wires in the car’s system.

In a vehicle with a factory-fitted stereo:

  • Take a multimeter and set it to 12 volts.
  • Secure the multimeter’s ground side in the dash
  • Now, turn on the ignition key to ACC
  • Examine all the wires
  • One wire must carry 12 volts
  • As soon as you turn off the ignition, it will take away the volts
  • Turn on the ignition again; the voltage must return
  • Hence, it proved that the wire is your 12V accessory wire

In vehicles with aftermarket stereo:

  • You can perform this test on the fuse box side or at the ignition harness
  • Take a multimeter and adjust its voltage setting to 12-volt.
  • Properly secure the ground point of the multimeter in the dashboard.
  • Now, turn the ignition on and check each wire in the fuse box or ignition harness.
  • One wire among them shall show an output voltage reading of 12 volts.
  • If you will turn off the ignition, the reading will disappear
  • If you turn on the ignition again, the voltage reading should appear again.
  • Such wire is the accessory wire.

The test makes it clear that acc wire loses its power when the ignition comes in the OFF position and works only in the ON position of the ignition.


The wiring harness plays an important role when installing an aftermarket car stereo. 

However, the harness must have corresponding connectors and wires to match the factory-fitted wiring seamlessly.

Suppose you want a customized stereo wiring harness or any other automotive wiring harness, contact Cloom

We are experts in manufacturing superior-quality cable assemblies and wiring harnesses for different applications.

I am Lillian Yang, having been a sales manager for over 10 years.

I have received many positive reviews from customers. They have praised our excellent service, on-time delivery, and high-quality cable assemblies.

For your projects, please provide cable assembly files/images/smples, etc., so that I can send you a quotation within 24 hours.

Contact me now and let’s get started on building your wire harnesses!

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