All:
I've researched this topic quite a bit on the forums, and while some of the info is great, I'm still not able to find the answer, in simple terms. Some of the posts I found looked promising, but the pics where gone!
My main question is, which wire in the plastic piece behind the rv mirror is switched 12v, and which is ground? I haven't been fortunate enough to find conclusively the answer for an 08. I've read that the green/white stripe wire is S12v and the brown is gnd, but others have said blue and white is S12v.
Does anyone know for certain?

Or at least give tips on how to use a meter to find the correct ones? Thanks a ton in advance!