At the genny, you will see a large battery cable going to the starter. Also on the genny frame, will be the neg cable running to the coach frame. 9 times out of 10, the neg cable will have a bad/corroded connection at the frame. Failing that, check both ends of the pos cable and the neg connection on the genny frame.
John & Clare Lyon
2007 43.5' Monaco Dynasty Palace III (All Electric)
Towd: 2011 Chevy Equinox