Taillamp out Message 2017 View

My 2017 View Model M gets a "Right Taillamp Out" message on the dashboard when I turn the lights on. The lights are not out, but the overcab amber running light are out. The message does not appear until I turn the headlight switch on. I am guessing the Mercedes dealer will not look at this since the overcab running lights are a Winnebago add on. I suspect that Winnebago has tied into the right rear taillight circuit to power the over cab running light thus kicking in the Mercedes side of things when the Winnebago supplied lights failed (or wiring)
Any suggestion on how to fix it and/or if M-B or Winnebago is responsible for it. I have gone on top of the cab and all the running lights look totally sealed and I would think not all bulbs would go out at one time which points to a wiring problem.
Thanks a lot for any feedback

If they tied into the rear tail light circuit and the rear light still works....not sure if this would activate the "light out" message.
Is your Right tail light a regular bulb or is it an LED ?
You could get the warning if you swap out a regular bulb with a replacement bulb that is LED.
The LED bulbs often don't put much of a draw on the electrical system and the computer thinks the bulb is burned out.

As for your overhead lights, I would put my money on a missing or broken ground connection.

I feel your pain chasing electrical gremlins

The right rear taillight still works. It is original which I assume is standard bulb. Thinking about that, I also assume that is Winnebago add on equipment that ties into the M-B wiring harness some place. I guess I would like to know where the overcab amber running lights get there power from. It seems like it must be tying into the right rear tail lamp to activate that dashboard message. I will try Winnebago to see if they can give me a wiring diagram that is meaningful instead of just the basic manual diagram that is worthless. I think you are correct on the bad ground connection, the question is where? As usual with these weird electrical problems, assuming the source of the problem sometimes has nothing to do with the real thing.
Thanks for your feedback

Our 2014 matches the wiring/reference diagrams we have from Winnebago and there is a circuit breaker labeled Clearance/Tail Lights in the panel below the driver's seat accessible with the door open.

Winnebago terminates the Sprinter tail light wiring at an interposing relays under the passenger seat. The relay coil does not have enough resistance, own it's own, to prevent the tail light out sensor so load resistors (the gold finned devices under the passenger seat) are used to ground the coils. I've heard of this before and it was caused by someone tying a ground from the Trik-L-Start to one of the resistor wires (instead of a mounting screw). Check the wiring under the seat.