Which wire is reverse positive?

I’m hooking up a back up camera and going to tap into the reverse circuit at the taillight, has anyone done this? I’m looking for the wiring color codes for reverse positive and negative, can’t seem to find them on the Internet. 2006 Sport.

 

I installed a wireless camera years ago but I don't remember the color, it seems to be white for positive, but not sure. It was easy to find, just disconnect the connector, put the car in reverse and check with the tester light. The negative either Connect to the body or use your om-metter to find which one.