“Do red and yellow wires of a car stereo go together?”
It is one of the most common radio installation-related questions I get asked.
And there’s no single-line answer to this question.
To understand this, we’ll have to discuss the functionalities of both these wires.
But before this, we’ve assumed that yellow and red are memory and accessory wires. While that’s indeed the case with 99% of the vehicle, some cars can have different wires colored as red and yellow.
To avoid this confusion, you should check your car owner’s manual (and go through the wiring diagram) or identify the memory and accessory wires through a multimeter.
Test Car Stereo wires with a Multimeter
The latter method can be helpful if you’ve lost the manual. First, you’ll have to find the ground wire (usually colored Black) and turn off the ignition key.
Then connect the negative multimeter lead to the ground wire and connect its positive lead to other wires one by one. Whatever wire gives you 12V reading with the key off is your constant 12V wire.
Once you’ve identified the memory wire, turn on the ignition and repeat this test. The wire that gives you a 12V reading with the ignition on is your ignition or accessory wire.
Yellow vs. Red Car Stereo Wires
The yellow wire provides a constant 12V power to the radio even if the key is off. It’s also known as the memory wire because it helps the radio to save different types of critical information such as current time/date, soundtrack, radio station, etc.
On the hand, the red wire is usually the ignition wire. It is the wire that triggers the radio to turn on. Unlike constant 12V wire, this one will only work when you turn on the ignition key.
Can you Put Car Stereo Red and Yellow Wires Together?
Yes, you can put these wires together.
During radio installation, some people accidentally damage the wiring harness.
This damage can result in bent pins for some wires, such as the red wire. As a result, the red wire doesn’t get any power from the vehicle harness. And the radio doesn’t turn on.
So to avoid this situation, they put yellow and red wires together in yellow wire’s pin. Since that pin is working fine, the radio turns on successfully.
Should you Put Car Stereo Red and Yellow Wires Together
But it’s not a win-win situation.
Remember we discussed that the yellow wire provides constant 12V power? Well, now that we’ve put the red wire in the yellow wire’s pin, the latter is also getting power all the time.
And this constant power means you can’t turn the radio off – even with the ignition off.
That’s why I don’t recommend people putting both of these wires together. Yes, now the radio turns on but it’ll drain your car battery from time to time.
The better solution is to diagnose why your ignition wire is not working.
Car Stereo Swapping Red and Yellow Wires
Many radio installers accidentally swap the red and yellow wires during the radio installation.
While it’s true that there won’t be any critical damage to the radio, it will mostly stay on all the time and drain the battery.
That’s why you should avoid doing this, too.
Frequently Asked Questions
What are the Red and Yellow Wires on a Car Stereo?
These are the Accessory wire and the constant 12V wire.
Is Red or Yellow Constant Power?
The constant 12V wire is usually colored yellow.
Is Yellow Wire Negative or Positive?
How to Find Ignition Wire for stereo?
Put your vehicle in ignition mode. Connect the negative multimeter lead to the ground wire. And connect the positive lead to other wires, one by one. Whatever wire gives you a 12V reading is the ignition wire.