The other day I helped a friend with an older Jayco Designer. He couldn't get the pump to stop running. It turned out to be a two fold problem. First of all it had three pump switches that he didn't know about; one on the main panel, one by the bathroom sink and one in the basement on the panel that has the water valve switches on it, and any one of them can turn the pump on. We finally got the pump to stop when we finally found all the switches, but that was only part of the problem. As it turns out the water pump itself was shot: apparently the impeller was either broken or sheared off the shaft. In either case the pump would not pressure up. If yours is cycling on and off then your pump is probably ok. It's either got to be an unknown switch on or a switch that is burned out in the on position. JMHO
