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How to Install Aux Input in Car Stereo?

Car stereos have changed a lot in recent years. Bluetooth has come to the front of the class, and it’s ultra-convenient as long as you have enough battery power on your device to keep connected. Plus, the best software to keep a solid connection.

But an even more reliable connection is the good ol’ AUX cable. Most new cars on the market still include an AUX cable, and here I’m talking about a 3.5mm (1/8”) male connector. This is the standard to plug into your phone, tablet, or another device.

However, some new cars and many older models don’t have this simple connector. But never fear. If you’re just a little bit handy and have a basic understanding of electronics, you can easily add one. So, here’s how to install AUX input in car stereo systems that don’t have them.

How to Install Aux Input in Car Stereo

Your Options

I don’t know much about skinning cats. But, what I do know is with any car stereo repair or modification, there is almost always more than one way to get the job done. Adding an AUX cable to your car stereo is no exception.

In a nutshell…

I can think of two main ways to add an AUX cable to a car stereo. But, there may be other options as well.

The easy way to do this is to use an RCA to AUX cable adapter. The less easy way entails connecting directly to a CD changer port. Both ways have their advantages.

Going through RCA is quick and easy, but only if you’re not already using RCA for another connection. Going through the CD changer is almost guaranteed to be an open route, but takes a bit more work to get the job done. Let’s look at these two options in detail.

Adding AUX to Your Car Stereo – The Easy Way

I call it the easy way, but you still have to know a thing or two about your car stereo system to get the job done. Essentially, what we are doing in this method is opening up your stereo and connecting an adapter cable to the RCA ports on the back of your stereo head.

Here’s how you can do it:

Step 1 – Remove your stereo head

If you’ve already changed or modified your stereo system, you should already know how to do this. So, you’re already ahead of the game.

If not, you’ll be looking at the factory stereo that came with your car. I can’t tell you the method for removing the head since all makes and models are different, and there are hundreds of different variations.

However, in general, you’ll find a way to pop off the face plate and then loosen off the screws holding the stereo in place. What you should do is Google “remove car stereo” plus the make, model, and year of your car. You’ll find detailed step-by-step instructions or videos to help you get this step done.

Step 2 – Locate the RCA inputs

RCA inputs are going to be located on the back of the head unit if you have them. They’re going to be labeled R and L and have red and white (or black) on them. If you don’t see these ports, you won’t be able to use the method. So, you can skip right now to “The Somewhat Less Easy Way.”

If you do have RCA inputs, you’re in luck. In this case, all you’ll have to do is plug in a Y-adapter to connect AUX to RCA.

Step 3 – Connect an RCA to AUX cable

RCA to AUX cable

What you need here is an RCA to AUX cable. Be sure it has male RCA pins on one end and a single 3.5mm AUX pin on the other.

You can keep it short or give yourself enough length to reach the rear for those backseat DJs. This gold-plated, PVC-coated flexible cable from UGreen comes in lengths of 3, 6, 10, and 15 feet, though six feet is probably more than enough.

Once you plug the two male RCA pins into the stereo’s RCA inputs, test it out by plugging the AUX end into your phone or another music player. You might have to adjust the input selection on your stereo to get the audio to work.

If things are working, excellent!

But, here’s a tip – tape the RCA cables in place with a little electrical tape. That’s because if you ever pull them out by accident, you’ll have to remove the stereo again to fix the problem.

Once that’s done, you can close up. But where do you run the cable? Most stereo slots will have space to run the cable out past the stereo head. However, you may have to drill a small hole on the edge (making a U-shaped groove) of your face plate to get the cable out neatly.

Choose an unimportant edge of the plate and drill carefully to make a neat groove just big enough for your cable. That’s it – you’re done.

Adding AUX to Your Car Stereo – The Somewhat Less Easy Way

If you don’t have RCA inputs on your stereo, or you’re not sure, there’s another method for how to install AUX in car stereos.

In this method, we’re going to solder an AUX cable directly onto your stereo’s CD changer input instead. For this method, you’ll need an AUX cable, Solder Wire, and a Soldering Iron.

Step 1 – Open up

Just like in the previous method, you can search for instructions or videos on how to remove your specific car’s stereo. Once you’ve done that and discovered that you don’t have RCA inputs, it’s time for the next strategy.

Look for your stereo’s CD changer input instead. This is a funny-looking port made up of usually 8-pin inputs. As long as you’re not using a CD changer in your car, and who is these days, this is another way into your stereo.

Step 2 – Locate the right pins

The plans for different stereos are different. So, again check the make and model of your car (or just the stereo) to find the pin layout.

What you need to find are the L, R, and ground pins for your connector. These are normally at the bottom of the pin array. But, they may not be labeled, so be sure to find a map or schematic to be sure.

Step 3 – Solder an AUX cable in place

Solder an AUX

Before you can connect an AUX cable to the CD changer input, you’ll need to first get yourself an AUX cable.

You can order a cable with an AUX 3.5mm connector on one end and the other end bare wires like this 6-foot one from Fancasee. If you want something more durable, you can get a braided nylon reinforced cable like this 3.3-footer from Syncwire. But you’ll have to cut one end off to get at the wires.

Either way, you’ll see three wires on one end of the AUX cable. They’ll be the red L-channel wire, white R-channel wire, and black ground wire. You can lightly solder these in place to the correct inputs on the CD changer port.


If you’re not experienced at soldering, try watching an instructional video and practicing first. You can use some scrap wires and try to solder them together until you get the hang of it. Just don’t use too much solder, and you’ll be fine.

Once the cable is soldered in place, test it out. Plug the AUX male end into your phone or other device and try to play some music through your stereo. Again, you will probably need to select the right input – the CD input on the stereo to get the sound to come out.

If it does, congrats! If not, check your connections. You may need to re-solder until the connections work.

Just like with the other method…

You now have to find a way to run the AUX cable out from your stereo. Once again, you may need to drill a hole or a U-shaped groove near the edge of the stereo’s faceplate so that the cable can come out cleanly.

Once this is done, close up and celebrate – you were successful at adding an AUX connection to your car stereo.

Other Options for How to Install AUX Input in Car Stereo

If you don’t have a knack for DIY, there are a few other ways you can get an AUX input for your car stereo.

If you have a USB input for your stereo, you can convert this to AUX by using an adapter. This adapter from AGPTEK goes from USB to AUX and should connect to any USB input on your car stereo.

On the other hand…

If you have an old car with a tape cassette player, you can get your hands on a strange-looking contraption. The tape cassette adapter from Arsvita gives you a 3.3-foot AUX cable that connects to a cassette tape adapter which can be played through your stereo’s tape deck. 

It won’t sound phenomenal, but it’s cheap and easy if you have a tape deck in your stereo.

Need Help with Other Car Stereo Issues?

If so, take a look at our detailed articles on Why Is My Car Radio Display Not WorkingWhy Car Radio Won’t Turn OffWhy Is My Car Amplifier Staying In Protection Mode, and How to Play Music from Phone to Car without AUX or Bluetooth for more useful hints and tips.

How to Install AUX Input in Car Stereo Systems – The Best Methods

There are some easy ways and not-so-easy ways to get an AUX input for your car stereo. If your stereo has a USB port, you can use an adapter there. If you have a tape deck, you can also get an adapter for it.

However, if neither of these easy options works, you’re going to have to open things up and take a look inside. Luckily, if your stereo has RCA inputs, you can use an RCA to AUX cable to connect to your stereo system.

But, if not, you have a CD changer input like on a lot of older cars. In that case, you can solder an AUX cable into those pin ports. Either way, you might need to get creative. But once you have, you’ll be the proud owner of a brand new 3.5mm AUX connection for all your driving music needs.

Until next time, good luck and happy listening.

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