Just wanted to thank everyone for posting to this thread. My wife and I have a 2010 Santa Fe which we got from her parents. It was one month beyond the five year bumper-to-bumper warranty period when we received it. It has a number of minor issues (all of which, of course, would have been covered under the warranty) including the problem with the map light "door" setting which everyone reading this thread is all too familiar. I debated how much it was worth to me in terms of dollars to have map lights that turned on when the doors were opened. I was certainly not going to pay to have the dealer replace the map light assembly. Thanks to the magic of the internet I came across this thread in which I learned for the first time that the diode in the map light assembly was the problem. After obtaining a new diode (1N5402) from the local RadioShack, and about 30 minutes of disassembly, soldering, and reassembly, I now have map lights which function as they should when the "door" setting is engaged. Thanks again to all who contributed!
(As an additional note, for anyone experiencing the same map light problem and debating whether they have the skills required for this repair - give it a shot. I would rate myself as average-at-best in terms of handiness, and I found this to be a fairly easy DIY project.)