Electrical problem

Thanks for the hints and advises. My best friend is an electrical engineer, and I will promise him a few brewskies for solving the problem. Once we find the relay, we'll be on our home run!

The relays that disconnect the house and chassis batteries are 'latching' type relays that will stay closed until they are electrically 'unlatched'. Sounds like your engine (chassis) battery disconnect relay has failed. I doubt the boost relay welded unless you were just using it to 'boost' a dead chassis battery to start the MH. Another possibility is the switch for the disconnect has failed and is no longer delivering the 'unlatch' voltage to the relay. You need to find the relay and jump 12 volts directly to the correct terminal to see if it will disconnect. Get the numbers off the relay and look for it online to determine which terminal you need to jump to (never put jumpers across things you aren't sure of unless you like burned fingers and seeing how good your comprehensive insurance policy is). As to finding the relay, have someone work the switch for the house battery while you nose around looking for where the clicking sound is coming from. MOST of the time the two relays are located together. Expect to pay around $75 online for a replacement if the relay has failed.

Probably has a round silver solenoid that is used as the boost and house battery charge relay. Very common for these to go bad. Sounds like yours have welded.

Charles
2007 Winnebago View 523H on a 2006 Dodge (Daimler-Chrysler aka Mercedes) Sprinter 3500 chassis. Bought Sept 2015 with 18K miles on it, Prog Ind HW30C, Prog Dymanics PD4645, Chill Grille, PML/Yourcovers.com deep alum trans pan, AutoMeter 8558 trans temp gauge, Roadmaster sway bar, Fantastic Ultra Breeze hood, added OEM parabolic mirrors and RH aspherical mirror.

It could be a bad ground under the step.