MasterCraft shower question...?

I have the boat winterized and in storage. I put both batteries back in the boat after being charged and noticed now that the shower wont work. I checked the breaker under the dash and it was fine. Im not sure where to check for voltage at the pump tho. Any ideas? Also, do they have a wiring schematic, kind of like a Haynes manual, but for boats?

So schematic, but its a boat, its really not that complicated.

Follow the shower hose to the pump. Turn on the shower switch on the dash. Check voltage at pump wires