I took down the rear speaker/light cover and on the driver's side there is a small electrical bar. The third from the center connects to the brake light. The other wire connects to the top left on the driver's side brake light push on four plug. You have to remove the spare tire to see it. I found a third brake light in the yards and painted it to somewhat match my interior. BTW I have not washed the tailgate since I de-installed my muffler. Put on over 140 miles in mixed driving. Straight out the back does not seem to make the tail gate sooty as predicted by some.