Battery Disconnect BD1 problems

[stkt]

Would appreciate any assistance, this problem is driving us nuts. 2001 Dutch Star.

BD1 (coach only, not chassis) stopped disconnecting 12 volts, and the light stayed on all the time. Here's what I've tried so far:
1. Replaced the BD1 and the disconnect relay
2. Confirmed the White Rogers coil is good
3. Confirmed the intellitec bi directional isolator is good
4. Pulled the solar panel out of the system
5. Cleaned all grounds

The Dutch Star (2001) has a master chassis power cutoff switch. When you turn the chassis switch to off, everything on the DB1 works normally.

Mark at M&M RV Electronics says there must be a battery isolator somewhere on the coach that has failed, allowing a backfeed to occur. 3 days working on this problem! Anyone have any idea if the coach has another battery isolator, and if so, where it might be?

["007"]

Take a look at the diagram in this post older Bird system and within this thread are other links to various coach systems.
Link found in QT's # 3.

[stkt]

Many thanks 007 for that quick response. Will check out the link in detail and see what we can learn.