Is the problem only in the rear, or the front as well?
If it's only in the back, check the drivers side light harness to make sure the wires have not pulled out from the harness. If it's both front and rear, the problem seems like it would be somewhere from the switch to the lights, which isn't exactly easy to diagnose unfortunatly.
Luckily, the only thing effected would be the tail lights, brakes and turn are on a seperate circuit altogether. Just uh, don't drive at nite...lol.