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Are you able to plug in now or start your generator? Did you measure voltage at the house batteries?
The generator will not start because you have VERY Low voltage on your 12 volt system. The very first place I would start at is the batteries. You mentioned that they where a little low on water, I would have these batteries load tested. Most Auto Parts stores will test these free of charge. IF you batteries test GOOD then I would unplug the coach and hook a digital multi meter up to the batteries, Plug the coach in and watch the meter,the battery voltage should be charging very hard around 14.2 Volts. After awhile it should taper off. Your unit has a Inverter or Conventer,this component is responsible for charging your batteries up. Each of these components will either have re-settable breakers or fuses near them, make sure they are good. Also you should have a breaker inside your unit labeled Inverter or converter, make sure this breaker is on. From the sounds of it your house batteries could be bad.
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