I had a similar problem with my 2001 Newmar Kountry Star. It turned out that the microprocessor for the rear air storage was faulty. Same issue, light and warning shriek came on and the tanks read empty. Would go back to normal after a short time, with air pressure going right back up to normal (so, I knew it was a sensor) and then faulting over and over. Replaced the microprocessor, which cured the problem.
However, a new problem developed that Freightliner could not (by law) fix. My odometer went from 80,000 down to 33,000 mi. Federal law prohibits it from being corrected, so now I have a sticker on the doorframe stating to add 44,000 mi (aprox.) to obtain correct mileage.
If you are going to change one of those processors, make sure your provider knows about the odometer glitch beforehand so your correct mileage is recorded.