Pin out stay the same for slave board. It has not changed whether a PS-2 5V or 3V engine. Pin 1 PCB Ground, 2 is PV, 3 M+, 4 M-. That last picture of a harness, has appropriate wire colors and looks like a 3V engine harness. Not sure how you are doing your testing, but I would trash that wiring diagram you made.
Do you have a ABA Unit you can look at? G