Hi guys I'm trying to install a forth flashing brake light and need helping identifying which wire is which on the tail light to tap into? Anyone ever done this or have any idea? Thanks in advance!

 

You could always grab a multimeter and check thay way.

 

I wired trailer lights on a Subaru the other day. All I did was stand back and look. That's brakes, that's turn signal, that's parking as my wife operated the controls inside the car. Hooked it up and it all works.