97 900S Left parking lights - short circuit

I replaced my left rear tail-light bulb without success. I determined that the fuse was blown, I replaced it and it blew again (and again....). I unplugged the wires from the taillight module and the fuse still blows. I have traced the wiring from the terminus back to a main wire harness and there is no obvious problem with any wire. Is it possible that the plug could be the source of the short? It looks like a simple termination point for 4 wires. All other circuits in the car are fine. The left hand parking lights (front and rear) are the only things that don't work. Your suggestions are much appreciated. RSS