You may have a failing circuit breaker in the line that leads from the alternator to the coach battery. On a previous Class B I had such a breaker that would make clicking noises as it broke the circuit and then reset itself repeatedly. When it "breaks" the line the coach lights dim because they are only getting power from the coach battery. When the breaker clicks in again the coach lights brighten with the power coming from the alternator. A coach battery being low on charge or weak would exacerbate this situation. In addition to brightening the lights the alternator will also attempt to charge the coach battery at the same time. The resulting higher current in the line may be enough to trip a weak circuit breaker. The breaker in my unit was located right beside the battery.
