Don't try this at home:
The cigarette lighter adapter and socket for my Garmin GPS 12 was corroded badly so I figured I would just wire it direct. I didn't realize that it reduced voltage down to 6-8 volts. It took several hours to fry the unit, but it did. 59 dollars later for a flat rate repair and 1 week turn around including 4 days of freight to/from Kansas I now have a repaired unit back in my hands.
Next problem: Garmin was unable to transfer any of the waypoints I had logged, and I didn't have them all saved to another source. I did have most of them saved to a file on my PC after seeing the list that Pillar had saved (that helped).

I already cried in my beer, hope to save someone the same trouble