I'm trying to install one of those blinker connections for the third brake light. The one where when you hit the brakes, it flashes that light 3 times and then stays on constant. My problem is finding out which wires are which. I need to tap into the brake signal, ground, and power. I looked and I have a green (power), black (ground), green/red (?) and black/white (?). So I have 2 out of 3. Anyone have any idea which is the brake signal wire?