the 110 volt receptacle you plug shore power into on the side of the coach, four screws holding it in. my receptacle has a led that lights up when you plug into shore power, if its not on their is a wiring problem. the transfer switch switches power from shore power to generator depending on what your using. the transfer switch is some where between shore power plug and generator probably under one of your bed storage or in one of the storage bins. its a black box about 10x10 possibly defective also.