I have a chassis wiring diagram that I got from Monaco ~6 years ago.
It shows all the wiring but it does not provide wire routing etc. It is detailed, it is a PDF file that I have to zoom into to see anything.
It is useful in that it shows interaction of the different systems, fuses, relays etc but I still have to figure out where everything is located. I've spend hours looking at trying to familiarize my self with everything. When someone post a problem I'll look at my schematic to see if I could potentially have the same problem, and will provide feedback if pertinent.
You can try and get a chassis wiring here
Some people say they've been able to get them, others say they don't get a response.