I cleaned out my holding tanks today after our trip. The gauge does not work on the black tank so I filled it until water came up in the toilet then pulled the dump valve and drained it. All well so far. I then started filling the gray tank. The first two lights came on so I kept filling to get a good flush. It took forever and the full light never came on. I was listening for any wierd noises. I heard bubbling in the toilet so I immediately shut off the water and sure enough water was coming up into the toilet.
On my old coach each tank had a vent coming out of the roof. I assume as this coach only has one vent on the roof they must have a tie in somewhere in the vent system. I will work on the warning lights on the tanks as this could be disasterous while flushing the gray tank if not being real careful.
Does anyone know if I am correct in assuming the vents from both tanks are linked together?