I purchased a 2001 Fleetwood Southwind 35R in 2010. I had it inspected by a professional company prior to purchase. I had about 41k on it, now has about 44k. Not driven too often. They did not find an...
I will describe operation of the hydro boost brake system.
Normal operation, Hydraulic power is provided by the power steering pump. A flow detector is used to insure the PS pump is working, if the PS pump is not workign the aux electrical pump is cut in to provide boost pressure.
You have either a bad PS pump (Which I am sure you would notice) or a bad flow sensor.