Thanks Mr Wizard for quoting cpmath. I didn't see their post, but you are correct in recounting my problem.
All I know is the chassis solenoid failed, and when it did, I lost all electrical power. The engine quit, the lights went out, and steering and braking were minimal.
Thor's techs and two very reputable RV dealers all agreed the solenoid failure caused a loss of all power. The NHTSA is investigating based on numerous complaints of the exact same problem.
I always thought that the alternator would keep everything going even if the battery was completely removed from the vehicle, so at first I too had a hard time believing the solenoid could cause my engine to die.
But proof was in the pudding, so to speak. The mechanic in Indiana recreated the issue. Every time he "failed" the solenoid manually, the engine died. We bypassed the solenoid, and everything ran perfectly. Evidently the design cuts ALL power to the engine.
teddyu,
I had minimal braking and steering, so I am not sure if power to the hydro-boost pump was cut or not. I do know the engine, emergency flashers, turning signals, head and tail lights and all markers went dead immediately. Pressing the battery boost switch didn't help. Jump starting the chassis battery didn't help.
The battery checked out perfectly. The coach electrical equipment worked perfectly.
K2kane,
Since there is a history of the solenoids failing without warning at highway speeds and the result is an immediate loss of all chassis power, I have to heartily recommend making the bypass permanent and installing a manual disconnect. The replacement solenoid is just as likely to fail as the original.
While it is a little more time, I can still disconnect the chassis battery safely without constantly worrying while I am driving, wondering not if, but when the power will fail and leave me dead on the highway again. I was lucky there was no one injured the first time.
