You now have links to 3 (slightly) different ways. Just be sure you have the 12v fused... where ever you get it.
If the prime switch is pressed at the same time the Onan "off" is pressed, it'll put that 12v straight to ground. (Not that it is that likely to happen... )
--
Mike Miller
`73 26' X Painted D.
`78 23' Birchaven
Hillsboro, OR