Well, there is more than one problem.
Latest issue, which the diagrams will help with concerns the water pump. It only runs if I hold the switch down (momentary-contact type of rocker switch).
I don't know yet if it is a bad sensor or switch. The switch next to the toilet "feels wrong" so I will pull it tomorrow and meter it out. If that is not it, then looks like I need to locate a water-pressure switch and/or whole pump assembly.
(Seems that a lot of parts that Fleetwood used on my '94 Southwind are no longer available or companies are out of business.)
But thanks for offering to help.
Bill W.