There is no one answer.... Different builders use different pumps and different wiring configurations. Some auto pumps use a "sniffer" circuit, the pump turns itself on every few seconds and check to see if it senses a load from pumping water, in which case it stays on until the load goes away. These pumps will eventually draw down the battery after many weeks of the "check" cycle, even if they never have to pump out any water. Some pumps use a mechanical float that activates the pump when water lifts the float. The main problem with these pumps is debris can stick the float and cause it to run dry and either burn up the pump or drain the battery. Other pumps use a set of contacts that activate the pump when the water level rises across both terminals. If the boat only has one pump and it is equipped with a auto float, the float switch should be wired directly to a battery so it is not dependent on the battery switch being on for it to function. The switched side of the pump is typically wired thru the battery switch so that it can't be accidentally left on, the pumps switch becomes disabled when the battery switch is turned off. Again, you'll need to research your particular setup, we've seen so many different combinations between different builders and different years there is no way to say there is any type of industry standard.
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