There may be exceptions, but RV owners manuals basically are a joke, if they exist at all. Keystone uses the same basic "owner's manual" for almost every Keystone camper they manufacture under their brand. (Same basic one in the last 3 of our campers). Being a 2000 model, chances are slim you'll find anything (but maybe not impossible).
What does exist are the manuals for the various appliances in your RV, refrigerator, trailer frame, axles, stove, water heater, furnace, and microwave if you have one and any other appliances you may have. New campers (like mine) didn't even have these manuals included. I had to search each one out via on-line internet to piece meal all the components of my current camper. I had no clue how to operate either television, no instructions included. No clue how the refrigerator worked (all electric), how the ice maker worked, or anything. Everything is now on-line internet item-by-item owner's manuals for each specific item in your camper. Frustrating ... ABSOLUTELY YES.
Forget about getting anything like wiring diagrams or plumbing schematic or anything like that. RV manufactures absolutely do not publish those type of documents.
I'm sorry to be the bearer of bad news, but "it is what it is."
Your biggest source of help is the internet, appliance and parts manufacturer web sites, and YouTube videos.
Yours being a motor home, you might get lucky and still have an owner's manual on the engine and chassis. Ford-Chevy-or other may be able to help you with that if you don't have the basic operators manual for the main chassis.