the pump and control box assembly is under the entry step. you can see the control box from the front and under the motorhome. if nothing works, look at your grounds and battery connections. winnebago doesnt run the rooms with the control box, even though the wires run thru the box. they only pass thru for convenience of wiring. the 40 amp fuse for the system is located in a #10 blue wire connected to the master relay. download a service manual for your system and go thru the diagnostics. use the led location sheet in the manual. other than that, all you need is a 12 tester. check the two bolts that hold the pump to the mounting bracket. if they are loose, you could be losing ground.