Hello & Welcome Desert Steve:
After thinking about your question,
I am assuming that you also have no tail lights as well as running lights, since you indicated that you only had brake and turn signals.
I think you should also check the wiring on the truck at the plug for power, the connection, the umbilical cord, into the camper. If you have an ohm meter you can check to see if you have continuity from one of the running lights to the plug on the umbilical cord. I had a problem on with my trailer and found that the wire on the truck had come loose at the plug.
I hope the suggestions help. Let us know what you find.