Add an Auxiliary (MP3/Ipod) Input to Your Car's Stock Radio

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Introduction: Add an Auxiliary (MP3/Ipod) Input to Your Car's Stock Radio

So you've got this great little MP3 player or Ipod, but your old-school car only has a CD changer? Sure you can get an FM modulator, but they don't work so great and are notorious for poor sound quality. I decided to leverage the CD player in my car to add a CD-quality auxiliary input for my MP3 player.

What you need:

-- Stock car stereo with a CD changer input
-- Basic Soldering Skills
-- Soldering Iron & Solder
-- Hand held Volt/Multimeter (to find right wires)
-- Small gauge speaker wire (anything around 18-14 gauge will work)
-- 2 panel mount 1/8" stereo phone jacks ($2.99 for 2 at Radio shack)
-- 1/8" stereo plug cable ($5.99 at Radio Shack)
-- Old pair of headphones (really just need the wire & 1/8" plug)

Essentially what you are doing is sending a pirated signal from the MP3 player onto the line that would normally be sending audio from the CD changer. In order to prevent a mixing of the audio from the changer & your new pirate Aux input, you have to play a special CD which contains tracks with perfect silence. It may sound complex, but is quite simple with some basic electronics/soldering skills.

Step 1: Remove Your Stock Radio From the Car

This is probably the biggest challenge in the whole project. If you do any work on cars, then your shop manual will help, but also there's tons of user forums dedicated to specific car models. Google around a bit and you should be able to find tips & help.

You may also try calling local car audio shops and ask them for tips on how to remove the radio from your specific make/model. Most are moderately friendly and will give you tips, just don't expect them to come do it for free or anything.

Step 2: Locate the CD Changer Plug & Pins

Locate the CD changer plug and gain access to the pins for audio transmission from CD changer to head unit. It should be something like the socket below in the lower right hand corner. They usually have about 8 or so pins arranged in a circle.

Now here's where you have to do a bit of googling. Figure out what the pin layout is for your radio's CD changer. Try searching with something like "Honda Accord 1996 CD changer pinout" I was able to find this layout for an Acura which was close to my Honda for the basis of mine. Remember, there's only a couple car makers, so there's a lot of similar equipment out there across brands. Honda Civic may be close to the Accord, and also close to an Acura. The same should apply for domestic cars made by the same manufacturer.

The 3 pins you need are:
Signal Ground
Left Channel
Right Channel

Step 3: Solder in Aux Input Jack

Once you have identified the audio pins, find a place to mount the internal jack. Using short pieces of small gauge wire, solder connections from the pins on the stereo to the pins on your panel mount 1/8" audio jack. Be sure to keep the signals correctly matched to the right pins so you don't end up crossing channels or ground.


Step 4: Mount the External Jack in Dash

Now that you have the internal jack mounted & wired, find a nice location in the dash where you will mount the external jack to plug in your MP3 player. Carefully drill a hole in the dash just larger than the jack to mount the external jack.

Use the old headphone cable and cut to the appropriate length to connect the internal and external jacks. Plug the cable into the internal jack, and solder the wire ends to the external jack. Take caution to match the pins (refer to plug layout diagram if needed) This cable serves as the quick-disconnect patch cable, should you need to remove your stereo or take apart your dash in the future. Soldering directly without this patch cable could be a pain later if you ever need to remove the dash or stereo for repairs, etc.

When drilling in the dash, be very careful and know exactly what's behind your drill bit so you don't accidentally drill into something important!

On mine, I had a spacer/junk bin that was right below the radio. This made an excellent location to mount the external jack since it was inconspicuous and also I could wire it up at my workbench instead of in the car. Choose the location you like best to mount the jack. Push the jack through your hole you drilled and use the nut supplied with the jack to screw onto the jack and hold it in place.

Step 5: Test Your Connections & Reinstall the Radio.

I'd suggest a test run before you completely reinstall the stereo to find it doesn't work. Hook up the cables and give it a try. If everything sounds good, install the radio and put the dash back together.

Once it's all together, all you have to do is put the CD changer on your "silent" CD, put it on track repeat and use the MP3 player to pump the tunes.

You can see here's my setup with the jack installed. Sleek and WAY better than an FM transmitter.

Step 6: Burn Your Special "Silent" CD

Now, in order to play the audio from your MP3 player, we need to trick the CD changer into thinking it's playing a CD. The stereo doesn't know that the audio is really being supplied by your MP3 player instead of the CD changer.

In order to do this we just burn a special "silent" CD. It's got regular tracks, but there's no sound played. Download the 5 minute "silent" MP3 below and create a CD using your favorite CD burning software. I took the same file and added it multiple times to the CD so that I had many tracks. Just fill up the CD with these blank 5 minute tracks so even if you don't have the CD on repeat, you'll still hear nothing from the CD and everything from the MP3 player.

Once you've burned the CD, pop it in your changer, put it on repeat play, and you're all set. Turn on your MP3 player and test it out.

At a cost of under $10 and 1-2 hours (depending mostly on how easily you can get your radio out of the dash) it is well worth the great audio you'll now enjoy!

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    user

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    0

    I have problem regarding the silent cd . I burned numerous of silent files on it but the volume is really low,almost 50% lower than normal. But,when using a cd with some songs on it, the volume is normal and high enough.The only issue is the backrground noice coming from the songs on the cd. Any solutions??

    104 Comments

    Did this for a 2006 Suzuki Aerio. It has a 6 CD changer feeding down to the radio/amp via a ribbon. So, we downloaded the parts manual for the CD/AMP combo, determined which pins were the CD signal pins, and soldered 26 Gauge wire to the ribbon connector pins (Braided the wires, but I wish we had just twisted all 3 together with the drill). It actually worked really smoothly except I burned the blank file to a DVD+R disk instead of a CD. We struggled with that problem for about an hour! Crystal clear audio, perfect volume, and no engine hum. Thank you Thighmaster!

    What a great idea. Head Units have moved on. Mine now has Bluetooth and 2 x AUX inputs (front and rear). But I still use CDs. I want to carry on using my CD Changer. How would I do a revers of this? That is, use the rear AUX input for the CD Changer? Guidance from someone who can figure this out very welcome!. Also, instead of solder, thought I'd use electric glue - I'm sure there must be some these days?

    2 replies

    aka_bigred is right, sort of. There is no easy, permanent way to do what you suggest. I assume you still use CDs because of the sound quality - I can't think of any other reason - so I see two options.

    The first is to use a decent portable CD player that can use a DC charger. If you want to make this somewhat more permanent and safer I'm sure you can figure out a way to mount it somewhere in your car, although if you want it to look good too you might have to get creative.

    The second is to rip your CD collection and use the files. If you go this route, I would recommend using a program called Exact Audio Copy to rip them as FLAC - if you're going to do something, do it right, and as a bonus even if you don't play them these files can be kept as a full-fledged archive for future use - and then use another program to copy and convert to mp3 en masse later if necessary. You can find more info on doing this sort of thing online. Then, play the files with an iPod Classic or some other portable player with a decent DAC (ie *not* most phones).

    You likely can't easily do what you suggest, unless your head unit already supports your CD changer.

    This instructable allows you to "trick" the OEM radio into playing your MP3 audio as if it came from the CD changer. What you describe would need the head unit to interface/communicate with a different CD changer that is wasn't designed to work with. Unless your head unit is compatible with your old CD changer, I think you're out of luck, or need to find some specialty interface to allow it to communicate with an OEM changer. Unfortunately, that's a completely different animal that what I've done here.

    FYI - they do make "wire glue" but I've never used it and wouldn't trust it to something installed into a relatively harsh, inaccessible environment like a car. You want the best, most permanent connection you can make, because if it comes loose 1) you'll have to pull apart the dash again to fix it, and 2) you might accidentally short out something else important if a wire's just loose & flapping around as you drive down a bumpy road. Wire glue might work elsewhere in a pinch, but you'd have a much better connection, and also have a very useful skill for the future if you lean to solder.

    I'm sitting here and wondering why I never came up with this awesome idea. Great stuff! Thanks for sharing!

    3 replies

    Hey... so i did this in my jeep and everything works.. except I hear engine whine when playing anything through aux jack.. any ideas?

    Had the same issue. It's your ground. Try finding a better spot or cheking your solder joints.

    user

    this is due to the cable your are using is not good quality coaxial cable, try replace this cable from a multimedia speaker input cable, these noise will go.

    could this be done without the cd changer unit? i have the head unit with the cd changer input pins but not the changer it self

    Probably not - the whole hinge point to this project is the accessibility to the CD changer input pins. I'd guess that on a standard stereo without a CD changer, these pins are all internal and accessing them would require completely dismantling the radio.

    I did it... All I did was cut and splice a stereo input jack into the stereo "out" wires for the head unit. They send that sweet sweet signal to my speakers and I blush. :)

    Can you explain more how you did that exactly?

    yes you can. the cd player module in any single cd player unit communicates (and therefore sends its unamplified audio) to the head units' mainboard and amplifier via a ribbon cable. you just have to hijack your ipd/mp3 player line onto the right points on the ribbon cable, and play a silent cd.

    This is a great work-around and I can finally listen to my own music in my Nissan Almera SX '06 (which only has FM / CD Player...) There's only 1 annoying issue that I have discovered - when a particularly quiet part of any song is playing, it is drowned out by static / interference / distortion. As soon as the song 'kicks in' or gets louder in any way, all of the above stops and plays perfectly. Any reason why it would do this? If you pause / stop a song there is no static / interference, it only occurs when there is a song playing during a quiet section / intro / etc.

    Hi and nice ideea!

    I tried to do this with my Jeep's radio but no sound from other source like iphone or samsung phone. This is my head unit, may be someone will have an ideea.

    Thanks!

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    question. say this works, but 3-4 months down the road the aux cord gets a short or rips, that means you have to redo this entire process?

    Our car's CD player is broken, so I don't care to keep the CD player an option. (This also means I can't play a silent CD) What would the instructions be to only allow our radio and the external audio device to work? Thanks!

    Thank you for the wonderful instructable! First instructable I've even actually done!