Nope, you have a broken ground wire. To prove it to yourself, look closely at those tail lights and you'll see both filaments, the tail light AND the brake light are glowing. If you remove the right rear bulb, the front ones, and possibly the side marker lights, the left rear one won't work at all.
Given the type of vehicle, it likely has a trailer wiring harness. That's the place to start looking. If someone spliced in that harness with Scotch-Lok connectors, you can bet the wires are corroded apart. Those connectors are used all the time but must never be used outside because they don't seal out moisture.
Monday, September 1st, 2014 AT 8:15 PM