Mazda Demio 2005 Converting MD/Tape input to AUX

Hey. I'm new here and I have a question. I've had a look around but can't see anything that helps with my problem.

My car stereo has a space for a MD/Tape, including and empty space, a button to switch to it, and a 16 pin port on the back to plug it in.

The stereo looks like the one shown here:
http://i572.photobucket.com/albums/ss164/Kozmos_ct/mazda 2/1e972011.jpg

I've purchased a 16-pin to AUX cable and plugged it into the port.
http://www.trademe.co.nz/Browse/Listing.aspx?id=879712893

I was hoping that this would mean switching to the MD/Tape channel would just work but the button is unresponsive.

My question is; is there something I need to do to hook up the MD/Tape button, some way to activate it?

I don't know very much about cars, but I know a little bit about electronics. I can solder something in if need be.

Take everything below with a BIG grain of salt, I haven't tested any of this:

Mazda, at least in the timespan of 2003-2009 or so, tended to use similar factory stereos across its entire product line. I used to own a 1st generation Mazda 3, which had a similar stereo, electrically, to the same generation of Mazda 6 (the "guts" were the same). The stereo had an option for the tape/MD input like your car, but it fit into a port on the bottom of the stereo (and not the port on the back). It required the "brains" of the tape/MD module to be there in order to activate the input. Back in the day, I bought and installed one of these:

http://www.sylfex.com/products/AuxMod/

It simulates the tape module and turns it into a plain aux in. Again, I'm not sure if it will work with your specific stereo, but it might be worth looking into.

You're right. The stereo does have one of those ports, and the device you linked to will most likely work, but if that is the only way to hook up the MD/Tape button, I'm wondering what the 16 pin port on the back is for.

I'd ideally like to know of a cheaper way than that to solve this problem.

If memory serves, the 16-pin on the back is for the optional CD changer or satellite radio.