Hacked Auxiliary Port For A Car Stereo

We’re not sure if [Apachem25] is just lucky, or if installing Auxiliary ports on most car stereos is this easy. The dealership wanted $95 to put one in, but he managed to add a 3.5mm audio-in port to his car stereo for just a couple of bucks.

The connector on the back of his head unit is a 2×4 set of pins recessed in a protective plastic ring. It turns out that the audio connector cable for a PC CD-ROM drive has a 1×4 socket that is perfect for this. [Apachem25] simply clipped one of those cables in half and used both ends to interface with the Aux port. He found the pin-out for his particular model on the Internet. He needed a specific resistance value between two of the pins to get the deck to let him use the input. All that he needed was a quick bit of soldering. The left, right, and ground are brought around the side and soldered to an audio jack he added in the face plate of the unit.

If you’re still rockin’ the cassette deck our favorite automotive Bluetooth solution is still this one for a classic Beetle.

[via Reddit]

29 thoughts on “Hacked Auxiliary Port For A Car Stereo

  1. This is likely not at all an isolated occurrence. Case in point… if you have a early 90’s Chevrolet vehicle ( 90 and 91 Trucks were tested by me) press volume up + fader up and also volume down + fader down to turn on Dolby noise reduction and some other feature that the dealerships charged extra for. It’s all about mass production, commonly features just aren’t turned on but it’s cheaper to produce everything the same.

  2. Some are simple, some are not. This one used a resistor coding to enable, like some usb chargers and phones do. Some use protocols, like the Toyota AVC-Lan or IE Bus (Similar to Can Bus) or the Pioneer IP Bus. No handshaking, no aux port.

  3. I want a CD changer emulator for my 1997 Ford Taurus. They exist for newer Ford radios and other brands. Small gizmos, put one folder on an SD card for each CD in the changer then load up to 99 MP3 or WMA (or other formats supported) into each folder.

    Plug the SD card into the emulator device then plug that into the CD changer socket. It responds to the CD changer buttons on the head unit, decoding the digital files to analog and piping the sound into the same input the original changer used.

    Ford sold a few million Tauruses and Sables and trucks from the mid 90’s to the early 00’s that used the same changer – which few people opted to buy.

    In the case of the first version of the 3rd generation Taurus and Sable, Ford never offered a single disc in dash CD player. Cassette was all you could have. Metra and Scoshe made (rather ugly, Scoshe’s is the best) kits to install a 1DIN radio in the cars with manual HVAC controls but there’s nothing aftermarket for the ones with electronic HVAC, though a few people have hacked up their “footballs” with varying degrees of success.

    A CD Changer Emulator for these Fords and Mercuries (possibly some models of Lincoln) would be a product that would sell if it’s not too insanely priced.

  4. For my old Kenwood head unit, I built an adapter that plugged into the CD changer port which had pins for left and right channels. Only needed a resistor to enable it as an input. Found all of the instructions online. It worked great, but could’ve used an inline amplifier because it was really quiet compared to other audio sources.

  5. That’s quite “known” ; those auxiliary are for CD chargers but the issue is that some stereo have analog in, some other digital in and some rare both… mine had digital so the solution was to get a pre made unit that would support USB mp3 & 3,5mm in :(

    1. Sometimes it’s better to be lucky than good. And you gotta build the aux-in hack for the stereo you got.

      But you’re right, it would be nice if someone cracked, debugged and published a nice CBUS interface, since that would also work with Nissan’s NBUS (or at least get me almost all the way there). So I wouldn’t have to do it all myself ;)

  6. The Mini Jack is called 3.5mm Jack in places using other systems than the imperial one.

    And yeah, the “HACK” is pretty standard, as this is standardized plug (C-Part of the ISO10487). The actual pinout is manufacturer-defined, tho. So it comes down to what headunit you are using. And those are not made by mopar or vw etc but car stereo manufacturers.

  7. It would be really great if Hack A Day added an option to filter out all the “from reddit” posts, since that’s about half the content on here nowadays. I don’t need to see everything twice.

    1. After a ton of research, looks like the same thing for my 2006 Dodge Caravan.

      I was hoping I’d be able to do something quick and easy like this, but instead I’ll have to open up the radio and see if I can do something like one of the older hacks (where you toss a jack between the radio module and the board)

      :( That’s a shame, but I’ll do what I have to. It means all I have to do is plug in and it’ll start up, instead of having to switch to AUX/CD Changer.

  8. Im trying to complete a similar mod on an 04 stratus. The factory unit does not include a cd changer. Just radio and single disk player.

    The 10 pin aux input (C-2) per internet research are labled,

    2.-AUX RT
    5-AUDIO RT
    6 AUX RT
    7 AUX LT 2
    8 AUX LT
    10 AUDIO LT.
    From a standard 5 pin input jack, I have run speaker wire from pin one (grd) to the radio pin 4 (audio common),
    jack pin “rt1” to radio pin 5 (audio rt),
    and jack pin “lt1” to radio pin 10 (audio lt.)
    This is all pretty standard from the multiplex of forums Ive scanned.
    I also have made a “silent CD”.
    The problem is the CD plays silent but no GalaxyS2 mp3 is heard over the car’s speakers.
    This hack is the only one Ive found talking about adding resistance.

    Voltage as follows:
    2AUX rt-1v
    4 Audio common- 0v.
    5. Audio rt-0v.
    6. Aux rt.- 12 v
    7.aux lt2- Neg 0.1-0.3v
    8.aux lt- 0 v
    9. aux return- 0v.
    10. audio lt. 0v.
    Of course the readings dont all seem to match their names…
    Please advise from what radio pin I should add resistance. Im assuming SDARS to something…..
    Help Please!

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