As NWJ stated, you may not find a wiring diagram for an RV.
If a fuse is blowing, it's a sign of a Short Circuit or a higher amperage draw than the fuse is designed to handle.
To check for a Short Circuit(wire contacting unit frame):
Example: If you're testing a light circuit.
1) Disconnect the wire at both ends(at the switch and at the light fixture).
2) Connect one lead of an OHMMETER to the unit frame(ground).
3) Connect the other lead of the OHMMETER to the wire you're testing.
If it shows continuity, the wirer has a Short Circuit(grounded to frame).