IMHO, in above drawing the [2ga RED (Chassis Harness)] wire that connects the two 120amp Breakers SHOULD be removed from Battery side of the Coach 120a Breaker, and installed on the load side of same. As drawn, if this [2ga. chassis wire] went to ground, the under hood breaker would trip/ disconnect from chassis battery, but the cable and COACH battery would FRY from the COACH battery, starting a fire. Rerouted, The GEN wire and chassis harness would then be protected from both batteries.