Onan generator has a plug in connection that is for remote start/stop convience. The cable for the swtich inside the motorhome is usually pre-wired by the factory. The final connections are usually made at time of a generator installation if so ordered. Many times the generator is installed at the dealership. The culprit for a no shut off issue is likely one of the two areas that connect the cable to the remote switch. The likely spot would be near the generator itself. There is a plug in port on the generator on it's outer shell. This connection is wired to the factory installed cable comming from the remote switch location. The three/four wires are probably spliced/soldered or just twisted/crimped together. At any case one of them is the ground wire that stops the gererator when called for. My vote is for a bad connection at that point since it is sbjected to all the road grime and weather conditions. It'l be a bear to get to, based on how you described crawling to shut it down. You may even have to drop the generator to get to it. But it will be well worth $$ your time to get to the connection yourself.
