What do you mean the aux input 'doesn't work'? What happens?
- Plug 3.5mm auxiliary audio cable into the Samsung Galaxy S3
- The headset icon appears and the phone is ready for audio output
- Plug the other end of the 3.5mm auxiliary audio cable into the car stereo's aux input
- The headset icon disappears and the phone plays music via the phone speaker as if there is no cable plugged in
Why does this happen?
So far, x3oiler over at bimmerfest.com has provided the best and most satisfying explanation I have seen.
"I suspect the galaxy is detecting open circuit. It needs some impedance to activate the audio.For what cars is this a problem?
The aux connection wiring is simple, but complex. It has from memory a 200kohm resistor across the head unit inputs to trigger the AUX function in the head unit. But to protect this "AUX trigger" resistance level the AUX socket audio signals are then capacitively coupled to the head unit. If this was not done, any device connected could reduce the 200kohm thus disabling the AUX function. This means that any device connected to AUX does not "see" the expected 100kohm impedance. This is quite ok for device that do not have intelligent output switching. The galaxy does have automatic switching hence a problem. You could fix by opening the socket and connecting a 100kohm resistor from each input to ground. Or maybe there is a hack available for the galaxy to override the automatic headphone detection."
- 2007-2009 Saab 9-3
- 2007-2009 Saab 9-5
- 2007 BMW X3
- 2007 BMW Z4
What can be done about this?
There are some 'fixes' but none that have proven to be a true solution as of yet.
- As x3oiler suggests, modify the connection to change the impedance by installing resistor(s). However I don't think anyone has documented this approach. If anyone has tried it, I haven't found a report on whether it was successful.
- Along the same lines as above, you could try inline resistor(s) in the actual 3.5mm aux cable. However, I haven't found an example of anyone doing/trying this.
- Download and run an app called SoundAbout (formerly called Headset Routing Fix) which allows you to force the audio output over the 3.5mm headphone jack or the phone speaker. While this can 'work' it is no permanent solution. Once you flip the headphone setting on, all audio comes out of the headphone jack. The volume resets to default headphone output levels. The music plays over the aux cable, but as soon as a song changes the audio output flips back to phone, then back to headphone once the next song comes on... and the volume resets again. This is an annoyance. Not to mention, you have to actually open this app and flip the headphone output on every time you want to use your aux output. You then have to flip the headphone output off to go back to normal. Unfortunately, my SGS3 wouldn't switch back to normal and was stuck on headphone out until I rebooted my phone.
- Another option is to reverse the polarity of the aux cable. This eliminates all issues and the functionality works perfectly... except for the obvious your polarity is reversed. Your lefts come out of your rights and rights come out of your lefts. It is actually a pretty noticeable and undesirable effect. However if you are cool to settle on this little sacrifice in order to get the aux cable to work as expected there are a couple of tricks to pull it off. Weenrock came up with one at androidforums.com: simply take two aux cables, plug one end of cable 1 into the phone and plug one end of cable 2 into the car's aux input. Take the remaining ends and lay them over each other so the black rings line-up. Tape it all together and you're done. If you did this really tightly and cleanly with electrical tape, it might be somewhat acceptable visually. Working off this idea, I decided to try the same concept but using a 3.5mm to Female RCA Adapter with a 3.5mm to Male RCA Cable. Sure enough, plugging the cables in with the polarity reversed works! The setup is bulky, but I like the idea of being able to pop the adapter in and use it with normal or reversed polarity at my will. Unfortunately, normal polarity doesn't solve the issue at all. I have yet to try doubling up on this idea and reversed the polarity twice. It very likely won't solve the issue, but it just might alter the resistance enough to do the trick without reversing polarity in the end. Ultimately that test would require 2 of the RCA adapters and one traditional RCA cable. It is very doable, but I only purchased one adapter so I can't currently try that.
- An interesting idea that I have not fully tested out is using an app called Headseticon which launches an app of your choice when it detects that headphones are plugged in. It also lets you set a custom headphone icon for the notification bar which is cool, but useless for this issue. Anyway, if you set it to launch SoundAbout, maybe you could better automate SoundAbout's switched of the audio output settings.
- Finally, some have found success using a dock that outputs to the 3.5mm aux input via USB. To me, this is not a solution but it is indeed a way around the issue. The negatives here are that the dock is pricey and the fact remains that the 3.5mm headphone jack should work without issue.