The Onans use a bunch of latching relays. You will need wiring diagrams from ONAN not Cummins. I take it this is a diesel.
Start Run circuit
Safety shutdown circuit
Both are needed.
Onan is famous for using 3 colors of wiring and ID numbers on the wire.
The plastic rings around wires are current sensors. Do not remove. Anything with a plug and socket should be unplugged and doused with Caig DeOxit D100 then replugged.
You need a ganged 240 breaker near the machine.
The generator must be enclosed with ventilation. It cannot survive getting wet.
Long term storage plug the exhaust with a rag. I strongly recommend a RAcor fuel water filter. If the unit has glow plugs I also recommend a push button over ride if temps approach 0°F.
Keep the unit high enough off the ground to make oil changes easy.
