I was making the electrical hookup for a Safe T Plus Trim unit so turned off the Chassis Battery switch. Then checked for the presence of voltage in the front bay before making the hook-up and found I still had battery voltage on the lug. Retried the switch but no change. Then turned off the house battery switch, heard a click and both house and chassis battery voltage were off. Turned house switch back on and house voltage was present but no chassis voltage (good sign). Then turned chassis battery switch on and got chassis voltage. Working fine since. I believe the Big Boy solenoid was stuck shut. Since it ties house and chassis batteries together when it’s engaged, when I turned off chassis batteries house battery voltage was still present on the chassis battery cables from battery switch on.
I’ll be verifying voltage going forward (and watching Big Boy for signs of failure).
Update: After re-reading the BIRD manual, it appears that if you are plugged into shore power (I am) and either set of batteries are at 13.3V (they were), the soleniod will be closed. If so, it seems one has to turn off both battery switches to get BIRD to release solenoid. Hmm...
