I have a Honda AM/FM radio in my 2000 Civic, part #39100-S01-A210-M1,
ref #MR529A0. I'm trying to figure out the pin outs on the interface,
mainly searching for the inputs for the secondary audio source - the
radio has a "CD/TAPE" button to accept aux input. The radio does not
have any controls for a tape or CD player, so I'm guessing that for
this very basic radio it just accepts the audio input, and the
controls for the aux input would be in the CD player or tape deck (if
I had one).

As you can probably guess, I'd like to connect a stereo wire to the
aux pins so I can attach it to an MP3 player.

There is a schematic of the pin outs on the radio body, but nothing
that is clearly the aux inputs. The closest is 2 pins labeled "ACC"
("accesory?"), but they are not labeled with a +/- or L/R. There are
many pins labeled "N.C", which I'm guessing are inactive. There is
also one pin labeled "AUDIO COM," but no second pin with that label.

Any ideas on how I could figure this out? Can you advise me on what the
pins
would be named, or where I can find a reference to decode the
schematic? Is there any axiliary unit that connects the factory car
radio to after market MP3 player.

Thanks!

VJ