I don't have " auto start " so I'm guessing here. Any chance that the coach batteries are low on charge? Converter not working correctly and the gen set fired up to charge the batteries, I know that being set to manual should override that function but could be worth checking. Also are you in , or have you been in , a heavy rain situation where water may have got to a control board or connections?
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.