Probably a stupid question, but I get the shower drain is run from the bilge pump through a y valve in basin locker. What I don't get is the switch on the front of the basin locker seems not to be needed it runs straight from the 12v panel. The boat is second hand to us, is it likely that this has been changed by somebody previously? So basically I can drain the shower but o Lyon be operating from the 12v panel, is the switch in the head stuck on?