I just did a bit of searching, and from what I can gather, it's retaining functions of the system (doorchimes, etc).
Take a look at this - Stereo Wire Harness Pontiac Grand Prix 06 2006 - eBay (item 110035688194 end time Aug-10-08 10:52:00 PDT)
There's just so much information out there. It's my understanding that a passive adapter won't do the job if I want to swap out decks. In order to keep the chimes/etc, I'd need to pick up one of the ridiculously expensive PAC adapters or similar. Is this a correct line of thinking?
