Anyone with stock HU and cd changer?

[Triften]

If anyone out there has an H250 or H260 stereo with CD changer (USA SPEC aftermarket) and can tell me how voltages on certain pins behave, I would be very grateful.

I'm trying to figure out what I need to do to fool the HU into letting me use the cd changer input as an Aux-In. I already tried dropping the voltage on pin 2 (CD ON) low via pin 5 (see www.hmaservice.com for pinouts) but that didn't work. Some cars require a pin to go high to switch over but before I shove 14V into these I'd like to get a little more info.

Thanks,
Triften

[jimatjtan]

I too have been working on this lately. I've discovered that the Hyundai CD changer uses a proprietary communications protocol on the BUS line to talk to the head unit. It is similar in complexity but does not match the Alpine M-BUS protocol. We'll have to send the proper data before the head unit switches into CD changer mode and plays the provided audio.

So far, I've figured out the protocol and built a microcontroller circuit that can decode what the head unit is sending out when it's looking for a changer. Now what I need to do is figure out what the CD changer's replies should be (which is going to involve a lot more guesswork). It would be trivial if I actually had a CD changer, but I don't really want to drop that much cash on this project.

If anyone's interested in my current progress, just drop me a line (jim@jtan.com). I've been busy lately but I do hope to get this working at some point.

-jim

keywords: stock H250 H260 H265 BUS CDON CD ON B+ M.Ground A.Ground R L N.C. aux input audio 8 pin din connector back