Hi Joe-
I recently replaced both the solenoids in my rig too. They were working just fine, but I did a "preemptive strike" because they were 11 yrs old and must have had a gazillion cycles on their copper contacts. There are better ones out there that use silver alloy contacts, but I elected to go with WGO parts (from Lichtsinn) ?? 11 years service will work for me.
The first sentence in John's post above is important in that the coach batt disconnect solenoid is a "latching" type solenoid. From the electrical dwg on your coach, it appears that this latching solenoid and its wiring is the same as on my Class C?..pictured below.
I took the old solenoid that I saved for a spare (force of habit, I guess) and tested it on the fender of my car today. It "works as advertised"; namely, when I applied 12v across the small small/armature terminals (momentary application, then release the B+ [positive] lead) the solenoid closed??and stayed closed without drawing any current. In order to get the solenoid to "open" I momentarily applied 12v to the (small) armature connections again, but in reverse polarity ?.. and the solenoid "unlatched"; I then had an open ckt across the large power terminals. SOooo, it needs powered closed and also powered open ...... as I see it, anyway.
I tried to get a wiring diagram/schematic (for the salesman's switch itself) from WGO tech support today, but all they seem to have are the "wiring and plug" type diagrams that are available online. I believe the "salesman's switch" that controls the solenoid is wired as shown below?.. makes sense. My coach is in Yellowstone now or I would pull the switch back and verify that. The switch sits in "neutral" and is spring-loaded to momentarily connect the solenoid as shown when moved to either the "On" or Off" position.
Assuming you have the correct configuration latching solenoid, you could have a DOA switch (even though new) as Gary stated; or maybe the salesman's switch itself (or associated switch wiring to the solenoid) is bad.
Pls check back with the forum re the outcome.......... we're all learnin'.
In any event???.good luck with the fix, and safe travels.