There should be an inline fuse on the positive lead going to the pump. As far as finding it, you are going to have to follow the water lines--the pump takes water from the fresh water tank, and will have a white plastic line going from the tank to the pump. If you can locate the drain line under the unit for the water tank, than you can estimate where the tank is on the inside, then look for white flexible plastic lines. It won't be a gray rigid line.
Double-check all the 12-volt fuses by taking each one out and looking at it with a light behind it--sometimes, very hard to see a blown element. This might be a good time to figure out what each fuse controls and label them...
2016 Tiffin 40 QBH
2015 38RSSA, traded
2005 TK3 #1869, 10 yrs of memories,
2017 F450 KR--one more Ford is it
2009 F450 4x4-died; 2010 F450-retired