wire broken in the harness for the hatch.if i remember the passanger side.I believe their may be a connector on one of the lamp sockets -don't remember which side but it should be obvious. It's a single wire and connector that plugs into the back of the socket.
Hmm I don't think they can technically ticket you for the third light being out. Whats the difference then say tinting the outside of the window. That would be legal. So if theres no light who cares as long as the two exterior lights work.I would be all dude no. You can legally black out the rear window as long as you have two side mirrors. No difference then not having that one light.