I posted this question on the Freightliner web site and several respondents said to look for access under the rear bed. I haven't looked at my unit as yet since it has been winterized and covered for the time being.
mine did the same thing,ended up being a switch up over the gen, funny thing freightliner said forrest river problem,, forest river said freightliner problem.. a small wire jumping across switch worked for a bit i ended up installing myself.
The engine cover is in the bedroom, in the floor just in front of the wardrobe closet. It is held by screws around the perimiter of the cover. Remove the screws and pull the engine cover up. It will be a bit snug.