Trailer owners manuals are very generic in nature. Very basic info.
With pen/paper in hand go thru rig and write down each component BRAND/MODEL then do an internet search for that 'specific brand/model service manual'
Download/print them out and build your own 3 ring binder of specific info
Here is one website by an RV Tech (Chris Bryant) -----great source for manuals. Chris did a great job putting this info together
Service Documents and Manuals