I've been playing with this off and on for a while now. Charging the house batteries while underway has never worked. Haven't done any long trips in a while so I wasn't in a hurry. So today I got into it.
The IRD relay board needs to sense 13.3 (?) volts from the chassis side to turn on the solenoid in the rear dist panel which connects the battery banks. With the engine running I am not getting 13.3 volts at the IRD board even though chassis batteries are at charging at 14.1 volts. After tracing for a while I found out I am losing about 1 volt going from the front dist panel through the dash and back to the front dist panel. So I took the wire going to the IRD and ran that to operate a relay. I ran a wire from the chassis 12 volt stud in the front dist panel through the contacts of the relay and to the IRD board. Now I get the full charging voltage going to the IRD board. That works good!
I check the EMS panel and I still don't show I am charging the house batteries.
Check the solenoid in the rear dist panel and I have 12 volts at the coil, with the engine running. Like I should. Check the big studs on the solenoid and they are not closing. I took the solenoid apart, had to grind the rivets out, and found one of the studs inside to be green as grass. Not letting it make contact. Everythings else looked fine. Cleaned everything up and put it back together. Works good.
Put it back in the rig and fire her up. It finally works. I don't think it had ever worked right from day one. The solenoid problem also explains why sometimes the battery boost switch would work and sometimes not.
Hope all that made sense.
Labor Day weekend here I come.