Big Boy is not charging Chassis Batteries

[vettehead]

I had trouble some time ago with the Big Boy relay not doing it's job, so after some research, I removed an cleaned the contacts of the big relay. Problem solved for almost a year.
Now I notice the chassis batteries are not receiving a charge hooked to shore power, 11.9 volts. Good charging rate with the engine running, 14.2vdc. House batteries are staying around 13.8 vdc while hooked to SP. Have load tested all batteries, good.
Thru research here I understand the ISO Green LED light in the Rear Run box should be lit, and a "hum" from the BB and it should be warm. Mine is not.
The question I have is what controls this part? Is there something that turns it off?

[Skip426]

I'm not sure if Monaco, uses a BIRD system ( Bi-directional Relay control module ) the 4"x4"x1" module should be clearly marked and close to the big relay, attached by a small gauge wire to the small posts on the big relay. Can you see anything with those markings?

[Gorlininc]

Yes. The ISO green light should be on.
You say you are getting a huum from the bigBoy?
Is there 12 V on the BB coil? If the BB is getting power then the BB is probably bad.
If the BB is not getting power to the coil then your BIRD is not operating.

are there any heavy drains on your 12v system? The job of the BIRD isolator when on shore power is to protect your house batteries from being drained down by your chassis batteries and visa versa. Your chassis batteries at 11.9 v tells me something is draining them down. I don't know how long they have been sitting. Why are the chassis batteries so low?

[Skip426]

The system also works in reverse, to stop high loads in the coach from running down the chassis batteries.

Operational info in this file , pages 13 & 14.