There will not be a diagram for that wiring. Mine was all done wrong in that box from the factory new delivery. That included the brake wiring that was wrong. Your best bet will be a test light and tracing.
Larry, Stephanie Park City, Utah
2017 31SL King, 8K axles, Disc Brakes,17.5 Goodyear H tires,BU Camera,5.5 Onan, Heated HT pads, Two Uniguard Awnings, Slide Toppers, 2000w PSW inverter