I'm going to ask the obvious question. Have you checked to see if the bulb is bad? There are two filaments in the bulb - one is for parking lights and the other it for the turn signal. I'm pretty sure the tail lights and the corner lights are on one fuse so if the fuse is bad your tail lights stop working too. Check the parking wire as well - I believe it's brown - as the parking and turn signal power travel over two separate wires.