Before you go anywhere else, look at the light fixture itself. Isolate the wiring completely from the fixture, and then check the wiring to see if another fixture will work properly. Be sure you have isolated both sides from the wiring to be sure.
If you find that the wires themselves will not work a totally different bulb and fixture, then, and only then, probe your wiring inside the unit.
By far, the most likely spot is in a light fixture itself.
Mike
2012 Winnebago Impulse Silver 26QP
2005 16.6 Double Eagle
2018 Jeep Wrangler JK
previously Snowbird Campers,
Triple E Motorhome and Fifth Wheel