Someone please tell me what color wires to tap into for power and ground and please don't tell me to get a voltage meter. This is a 2015 mustang gt base model only. I only want to tap into mirror not fuse box.

 

I just did this on my 14GT - so don't know if you have the same mirror - but for mine, the switched 12V was pin 1 (had a larger blue wire going in) and ground was pin 4 (black yellow wire in). I have a 16 pin block.
it works a treat - comes on with ignition on and switches off when key out and door opened (like the stereo)
good luck!