No power to Start 4K Generator in Fleetwood Terra 31C ClassA

There shouldn't be power to the hour meter unless the generator is running, since that's what makes it count hours. I don't know offhand if the start/stop switch common lead is designed to be at +12V or at ground. It may well be ground by design.

Some models and variants of models of Onan generators have a 12V fuse on the generator for the control board. It's usually fairly readily accessible on the generator, somewhere in the vicinity of the on-board controls and AC circuit breaker. Not all are so equipped.