I have a 2007 Itasca sunova 35J house batteries charge when on shore power as well as when the generator runs, but not when driving. I've looked through the web and found that it's possibly the sol...
With the engine running and shorepower/generator off, meter the house battery voltage. Then press the auxiliary start button and see if the voltage goes up. If it does, then the solenoid is ok, but the connection that engages it when the engine is running may be disconnected, broken, or corroded. It may be easier to just run a new wire if the existing wire is hard to trace.