I suggest you check the headlight switch first. If you can access the back of the switch, just take a look to make sure you don't have a wire loose or broken. The HL switch probably turns the marker lights on along with the headlights. Also, I would think the headlights will be on an automatic resetting circuit breaker, while the marker lights are more likely to be on a fuse. Just winging it here; whaddya think, guys? Good luck, let us know what u find.Dennis
While we're on the subject of lights, the best auxilliary driving lights I have ever used are actually aircraft landing lights, intended for small private planes. They are 12 volt sealed beam lamps, about 4 inches or so in diameter. They fit "Unity" lights that we used to attach to bumpers back in the 50s and 60s.