It was a bad ground connection - nothing to do with downstream 12V+ wiring.
When I pulled the nearby working under overhead light and used that ground, this fixture worked. The ground wire for the non working fixture had melted in the connector.
I am not used to working in the 12V world where an uninsulated wire is used for the other 1/2 of the circuit, but I guess that is the was it works in RVs.
I will post pictures tomorrow but BFlinn181
is the Winner - Winner - Chicken Dinner!!!