Ok, I got new batteries (2 6V GC2 Duracell from Sam's - 110Amp Hrs each) and when those didn't solve my power step inop issue I used the Battery Control Center troubleshooting guide that loulong sent.
Unfortunately, I didn't figure out what the problem is yet.
Here's what I did/found:
Both the chassis and coach batteries are charged.
When I push the disconnect switch for the Coach, there is power to the solenoid under the hood.
When I push the disconnect switch for the Chassis, there is NO POWER to the (other) solenoid under the hood.
I checked all fuses under the hood and in the coach (under the fridge)
I also tried turning on the key to see if I could get the ignition override to turn on the Chassis circut but that didn't work either.
I isolated the energize wire (purple) and the de-energize wire (gray) and checked the first section for continuity and it was fine. I also checked for voltage at the last wire harness connection before the harness went into the coach at the front right corner and didn't get any voltage when I pushed the switch.
I also checked the switches themselves and they do have continutiy when they are pushed. I didn't check for voltage (should have) at the switch.
I still have not found what I would consider to be the 'Battery Control Center Electronic Circuit Board' - just the relays and fuses underhood... I see nothing that looks like a circuit board - anywhere. I looked behind the coach batteries, under the hood, near the steps, under the fridge (fuse box 120V and 12V and converter behind flip down circuit panel)... Nothing....
Perhaps I'm not seeing the forest for the trees but I just can't find the controller circuit board.