[trit21]

All the yellow wires behind the helm are DC ground points. All yellow in the bilge are DC ground points. I would start at the batteries and make sure they are connected without issue, same for starter, alternators, regulator, ground on engines and battery charger. Then move to the Cummins alarm board behind the helm. Found alot of issue with those connections as they were corroded and not making great contact with intermittent alarm errors. Then move to the back of the tachs and the rest of the wiring grounds for the gauges.