There are 3 wires on the mirror. Outside going in, 1)(closest to the outside ) cannot really tell the color (tan or brown) 2) Black (ground) 3) (closest to the middle of the plug) again looks brown or tan
Anyone know which of the wires is hot 12V I should use. My Multimeter died and I need to get a new one, I was hoping someone else has done a mirror tap too.

 

My radar detector is powered via a mirror tap, and that's the pic of my connector.

Red tap goes to the brown closest to the outside (your #1)
Black tap goes to the black ground (your #2)

 

And here's the wiring diagram from the service manual if you were interested.

 

Did not feel like pulling the A pillar. Bought the tap and wired as diagram and picture Works fine for a 2014 TL w/ advance. Thank you.