Four pin plug is the audio OUT from the radio (aka Rear Speakers). One pin is unused. BMW # 83 30 0 413 584 is the "repair plug" that mates with it. The grey w/brown stripe is the ground, grey w/white stripe is the right speaker, grey w/red stripe left speaker, grey w/black stripe is not used. Application: http://www.bmwlt.com/forums/attachment.php?attachmentid=31006
The two pin plug is the audio IN from the Nav IV/GPS (this will "override" the radio audio if active).BMW # 83 30 0 402 343 is the "repair plug" that mates with it. It's mono, so if you're feeding from a stereo out source, you'll need a couple resistors. https://plus.google.com/photos/117838774173346589853/albums/5609335131898272801?banner=pwa
The three pin plug is the supply power to the Nav IV/GPS BMW # 83 30 0 413 585 SHOULD BE
the "repair plug" that mates with it. It has a (pin 1) Brown = ground, (pin 3) Red/White = +12V and (2) Blue/Green = Speed Pulse wire that tells the GPS how fast (slow/fast) the M/C is going (this is to tell the GPS to increase its volume). I used that to power my tablet's charger. (can't find where I ordered it, so I'm not sure about the part #)http://www.advrider.com/forums/showthread.php?t=201982
Hope this helps.