Overhead harness pinout for accessories?

Does anyone have pinout information for the overhead / dome light wiring harness in a 2010 III? I'm trying to wire a radar detector in to this harness on a switched 12v line. Initial tests look like pin 1 is GND with pin 12 maybe being a +12v, switched line, but I wanted to check to see if anyone has done this. Made the same mod on my 2003 RAV4 and am looking to duplicate on the Prius.

Thanks in advance.