This topic is really a pet peeve of mine. If I need an owners/repair manual for just about anything I buy I will either get one with the product or can download a replacement online.
The RV industry is severely lax in this regard. Owners manuals for a specific model are rarely if ever available, and forget about getting detailed repair manuals. You can't get schematics for electrical, water, etc.
The worst part is that not only has the industry not woken up to the concept of providing these but they have proven to be unresponsive to requests for a future correction.
I can only suggest that you unscrew every access panel, remove every cover, and haunt every RV forum in an attempt to understand the complexities of your particular coach. This has helped me immensely over the years and given me the insight and confidence to work on, repair, or modify my 5er.