Rear running lights not working

cgmartine wrote:
The most simple and easiest way to check it is to run a temporary ground wire from the nearest grounded point to the ground point on the inoperative light. If it works, then you automatically know it is a ground issue. The solution in that case is to run a whole new ground wire. If providing a solid ground wire does not fix the problem, then you have no dc power, and will need to supply it, preferably from a good known source.

Good advise for when you can get the wires to the lights. Unfortunately those high mounted lights are generally very difficult to re-wire. Hopefully the trouble can be found below.

Given the rear high mounted marker lights work as parking lights, the wires most surely will be routed from top to bottom inside the back wall and connected down below under the RV, pending the rig catching a rear tail light along the way. Given how and when Kathy's lighting issues surfaced, I would think her answer will be found underneath the rig near the rear bumper.

Of coarse I could be wrong, but that is the best place to start debugging.