Onan Emerald Help

[Countryboy47]

Hi everyone!New here so please bear with me.Ive got a 2006 Coachman Adrenaline toyhauler with a Onan Emerald 5500,348 total hrs.First RV for us and we love it.It has developed problem I cant seem to figure out.The generator wont start intermittently.I have run it on a regular basis,but almost invariably,when we need it, it wont start.Nothing!No clicks ,the fuel pump wont run,nothing!This has happened two years in a row at Leesburg.I have checked all I can think of.I am a very good mechanic ,and pretty good electrician,but I'm stumped.I've checked with a multi meter and test light.I noticed that at the unit I have 12 volts at the input,but when you press the start button on the gen itself the voltage goes away.It comes back a minute or so later?Wondering if the power converter has anything to do with it.Anything you guys can come up with is appreciated!BTW,I have already replaced the control board in the unit thinking that was the problem.

[markb5900]

Almost sounds like your start button has a short in it. Can you jumper around it and see if it starts then?

[Countryboy47]

Wont start at the inside board or at the unit start button either.Same symptoms at both terminals.Unit is mounted up underneath the camper so it is a bear to work on.Hoping I don't have to drop it.Almost seems like a wiring problem,but the voltage disappearing at the unit makes me wonder.I really don't know that much about these side by side electrical systems.

[Countryboy47]

I'm going to replace all the incoming cables from the batteries and check all the connections before I drop it down.

[markb5900]

Just did some google work and it seems pretty common to see full voltage at the gen, then when you try to start it drops out.
Most posts say:
1. Battery is just weak
2. Bad connection at the ground
3. Bad connection at the hot at the battery.
I would check the ground at the gen and where it attaches to the trailer.