OK, I'm Back. The two reading lights are fed by a brown and a white wire. White is usually the ground on the 12v
stuff in mine. These wires run under the end cap and up into the center of the ceiling. Next to the front vent, on the curbside, under the center ceiling panel, all of the brown wires are twisted together in a big, messy bundle. The ceiling light at the vent is also fed from this bundle. A good guess would be that this bundle has worked itself loose, or that the ground is bad. The ground is bundled in a similar manner. The ground wires can be tested with a multi-meter to the frame of the camper.
Let us know if this helps.