I'm not sure which 3 running lights you're referring to. If you mean the turn signals, only the 2 fronts function as running lights, and in the rear only the tail light should be lit.
(We already solved 2/3 of your problem right there. Ain't we good?)
Check the filaments in the bulb first, then look for corrosion in the socket, then follow the 3 wires into the harness near the steering neck and make sure they're connected.