If the chassis battery is just down a little, but enough that it will not start the RV, the emergency switch should provide enough juice to the chassis battery from the coach batteries to start the RV without running the generator. However, it sounds like either your chassis battery is too discharged to start the RV even with a boost from the coach batteries thru the emergency start switch, or your Trombetta is not opening or your 100 amp engine breaker is tripped.
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