in your engine bay, where your batter is, if you take your battery out, this will be easier to get to, but if you are looking at your battery straight on from the front of the car, look about two inches to the right of it, and go straight down, you'll see a circular black rubber thang'y, hahaha, that's about an 1 1/2 in diameter, that plug goes straight through the firewall just pop it off, that's for the passenger side, but i find it cleaner since you don't have to drag a wire from one side of the car to the other in the engine bay, good luck.