When I flip the switch in the dc panel to power the helm electronics box the fresh water pump runs. Even when freshwater switch off, this is the only switch this happens with. Anybody else seen this? Just started happening
Since it just started happening, it sounds like the switch failed in the on postion. Weird as they would normally fail in the off position. But, since as you said, it just started happening, that seems like the only answer.
Are you sure it is the FW pump? If it's the washdown pump, then the washdown switch on the helm panel is on. Troubleshoot by turning off all DC switches except the master and then turn on the FW switch and open a tap. If it happens with the helm panel switch, then someone has added wires to that panel or there is a short in the back of the main electronics panel in the cabin. Not likely. Check all the switches, particularly the washdown and baitwell switches on the helm panel.
My shower sump pump failed in the open position. Was always running when DC breaker was on. Replaced the float switch (Rule $40) and its fixed. Maybe not exactly related but switches definitely fail in open or closed position.