Car Stereo Can I Connect Red, Yellow and Black Wires Together
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Whether you just purchase a new car stereo and wish to install it by yourself, or you are trying to install an old stereo, you need to figure out where the red, yellow, and black stereo wires should go. 

In this article, we will show you how you can connect the red and yellow wires together for a car stereo. 

Here are the purposes of each wire:

You should not connect the red, yellow and black car stereo wires together. The red wire is for the accessories power 12-volt ignition, which can be attached to the stereo. The yellow wire is for the constant power 12-volt battery wire, which should be attached to the stereo for power and the positive battery terminal. The black wire is the ground wire and will ground the stereo.

Let’s get into more details.

Where Do the Red, Yellow and Black Stereo Wire Colors Go in a Car Stereo Installation?

This is a more detailed overview of how you can connect the car stereo red and yellow wires together:

Typical stereo wires are red, yellow, black, blue, white, purple, grey, and orange. However red, yellow and black are the most important. Here is a breakdown of the connections:

Red Wire: The red wire is for the accessories /switched power 12-volt ignition, which can be attached to the stereo and the positive side of your cigarette lighter socket or some other location near the head unit. This wire is powered by the ignition and turn on or off with the key.

Yellow Wire: The yellow wire is the new constant power 12-volt battery wire, which should also be attached to the stereo for power directly from the positive battery terminal (with an inline fuse). This wire is always hot and keeps memory.

Black Wire: The final wire, the black wire, is the ground wire. This wire, once attached to the stereo, will help ground it.

Can I Connect Red Yellow and Black Wires Together

To summarise, the car power wires are as follows:

Power Wires

  • Yellow Wire: Constant 12V / Memory Keep-Alive
  • Red Wire: Accessory
  • Black Wire: Ground

Head Unit Will Not Turn On Unless Red And Yellow Wires Are Connected Together

Is your head unit only working when the car stereo red and yellow wires are together? In some cases, you will find that the head unit of your car will not turn on unless the red and yellow wires are connected together.

car stereo red and yellow wires together

If your car stereo only works if the red and yellow wires are connected, then you have an issue.

In fact, you may find that if you connect the red and yellow wires together, the head unit will not turn off even if the car is turned off. In some cases, you will still have this issue even if blown fuses are replaced. 

Troubleshooting

Here is how you should go about troubleshooting this issue:

Since the head unit isn’t turning on unless both power wires are connected together, the issue is that the accessory wire (red) isn’t seeing any power from the vehicle harness.

can i connect car stereo red and yellow wires together

To fix this problem, you need to do a few simple checks:

  1. Check all the fuses
  2. Check the voltage of each wire. Check for volateg at the yellow wire, it should be +12 v unswitched. This means it should be powered all the time whether the key is on or off. The red wire should be +12 V switched and black is -12 V over and over again. If any of these have an issue, then a fuse if bad or the wire is bad. 
  3. Disconnect the wiring harness and make sure all the pins aren’t bent. Also, ensure that they line up with the factory harness. If you have to, remove them and reattach them carefully.
  4. Finally, check the wire on the vehicle side of the factory harness. These wires line up with the red accessory wire. You should check to ensure that the wire is not getting any power when the car is on. 

Fixing The Issue

To fix the issue, start by disconnecting the red accessory wire coming from your radio wire harness. Disconnect it from any other connection to the vehicle. However, leave the yellow constant wire connected to the yellow wire on the aftermarket wire harness. 

Now take the red wire and splice it into an accessory or ignition wire from the ignition harness or behind the fuse box. Now, run that wire to the red wire on the radio harness.

Ensure that you are using a wire strong enough to handle the current. You will want to use at least a 16 gauge wire. In addition, put a maximum of a 10amp fuse immediately coming from whatever wire you’ll be splicing into.

In some cases, the cigarette outlet may lose power when you turn off the car. If this is the case, simply splice into that power wire as well.

In general, also ensure that you do the following:

  1. Proper grounding. Ensure that the ground is connected tight and that paint is cleaned off the surface where the ground connects to the car.
  2. Ensure that there is no blown fuse.
  3. Ensure that the yellow wire to the radio is tightly connected.

FAQs

Can I Connect Red And Yellow Wires Together?

You should not wire the red and yellow wires together because the yellow wire should be the constant power wire and the red wire should be triggered by the ignition.

If you do this, the head unit will remain on and this will drain your battery. The car will not be able to start if that happens. 

Why Isn’t My Aftermarket Radio Working?

If you are installing your aftermarket radio and it’s not working, you may assume that the connections are wrong and so you may be wondering if you can connect the red, yellow, and black wires together.

If there is an issue with the wiring, the radio will certainly not work. In addition, blown fuses can also cause this problem. 

Swapping Red And Yellow Wires On Car Stereo

Is swapping red and yellow wires on your car stereo a good idea? No this is not a good idea.

The red and yellow wires have different purposes and produce voltage in a different ways. The yellow wire is for content power directly from the battery and the red wire is for switching power from the ignition.

Where Does The Yellow Wire Go On A Car Stereo

So where does the yellow wire go on a car stereo? The yellow wire is the constant power wire or the 12 volt battery wire. It should be attached to the positive terminal of the car battery and attached to the power terminal of the car stereo.

What If The Yellow 12 Volt Constant Wire Stops Working?

What can you do if the 12 volt constant power wire to your car stereo stops working? If the yellow 12 volt constant power wire goes dead, meaning there is no voltage, then your stereo won’t work. This may be due to a blown fuse or a bad wire.

To quickly fix the issue, you can get power from another 12 volt wire in the car or run a new wire from the battery. However, do not use the red stereo wire because this does not produce constant power.