Basically the O2 and ODAC has a terminal place for wires to connect to output its signal, instead of them being DIRECTLY JUST connected to a switch, they will all be connected to a custom PCB that then leads to a switch so the PCB itself has instructions on where signals go. There is stil that switch but it is not DIRECTLY connected to the amps terminal. It is connected to the PCB.
Still somewhat confusing, but I'm too lazy to explain so I shouldn't really be criticizing you, although I don't have much of an idea of what's going on either. If I'm understanding correctly, we are using a microprocessor to turn the units on and off.