<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by PARAGON:
It would seem that the stock head unit is set up for XM and if you could figure out how to add it to the Bus it would "receive" the signals from the XM receiver and show up as the Aux input. I am having a Deja Vu moment, though, and seems I have been through this before. <HR></BLOCKQUOTE>
That's exactly how it works. I have all the wiring diagrams. There is a second set of input pins (L, R, and common) that is unused and empty in the radio head unit connector. These are used for either the XM Radio Module or the AUX 6 CD Changer. The XM Module or the 6 CD Changer also connects to the Class 2 Data Bus to "announce" the device to the rest of the system. That's how the head unit knows to display the options for the extra device.
Right now the GM XM Modules are like hen's teeth. I still think the official XM Radio GM setup, called XM Direct, will be a good setup.
Here's the BMW version of XM Direct:
http://store.myradiostore.com/xmdireforbm.html