Chev chassis have a battery wire going straight to the starter. It should come off the chassis battery.
In the battery control center is where the battery disconnect relays are. One is for the power to the ignition and fuses under the dash.
One thing to check, make sure there is no resistance between the grounds on the chassis and battery system. I installed a ground (#4) between the two grounds.
I would suggest marking the cables with marking tape. Grounds should be Black and the positives red. I do not know why RV companies do not mark correctly.
Does your genset start and stop?
