Originally Posted by bergen
Coach batteries are dead. The chassis battery is hot (charged). Vehicle will not start.
Charged up the coach batteries and it fired right up.
I have a 2016 Vegas 25.2 that has done something similar. On the Ford side there is a relay that closes to feed power to the chassis when the key it turned on (same as a normal car). On my unit this relay appears to have a very high voltage setting. IE: even though the chassis battery tested good
the relay would not close and as such I had no power to anything even the dash lights. Put a trickle charger on for 20 minutes and that was enough for the relay to close and the MH started up normally. No idea if later units have this high voltage requirement relay or perhaps mine is faulty (I plan to change it out just to be safe)
IF the above was the reason for the non start then the connection to the coach batteries is the BIRD or whatever battery disconnect is used. When you charge the coach batteries, once the voltage reaches 13.2v the BIRD closes the Trombetta which ties together the coach and chassis batteries. Thus the chassis battery gets charged to full voltage and in a short time the MH can be started and everything will appear normal. (I had that happen to my unit as well)
In my case the BIRD was wired incorrectly from the factory and it caused all manner of issues not the least was draining batteries to the point the unit would not start.