[Richard]

First, this is the BEST post I have ever read when asking for help. You certainly grasped the arm chair problem solvers are no better than the info provided.

Let’s start with the Echo charger. You are absolutely correct. It is wired incorrectly and will not work as wired. It is a simple fix though. Remove the SO orange wire from the lug where all the chassis batteries are connected. Connect it to the Merge relay on the house battery side. Conveniently, there is already an orange wire on the merge relay. I think that will fix your charging issue.

My photos will not do you any good. My setup is different and I have changed some of the wiring to accommodate the lithium setup.

The foreign switch is connected to a device that changes how the tow car plug is wired. Foreign is a four wire plug with separate turn signal and brake lights. Domestic is the old three wire setup with turn signal and running lights using the same bulb in the tow car.

I believe, but may be wrong, that those wires were connected to a shunt for measuring amperage in or out of chassis batteries, and to measure chassis battery voltage. The old Xantrex control panel allowed you to see the amperage and voltage on Battery Bank 2. If the inverter and control panel were replaced, that function may have been disabled. Remove the panel where the inverter control panel is located and look for those four wires.

Again, this is a guess cause Newell did it as many ways as you can imagine. Two switches on the house batteries allows you to turn off power to the inverter, and turn off power to the rest of the systems on the coach that use 12V such as Aquahot controls, lighting, and AC thermostats.

The two thin wires to the chassis batteries may provide the voltage read to the inverter panel.

Here is my recommendation after you get the Echo wired correctly. Turn off all the batteries, disconnect the positive wires at all locations you can find, and use your Ohm meter to identify where and what each of the red cables is attached to.

Why? First Newell had some interesting logic in how they wired the 12V systems. You need to have a schematic. Don’t bother asking them for one. Second, you do NOT know who has had their hands in the wiring and what they may or may not have done. If you are going to keep the coach, take the time to make a map of the 12V system.

I did, and I was surprised at what I learned. It was very different than what I imagined.