Ender 3 problem.

[AutoWiz]

I am an auto mechanic and in the automotive world idle air control valves have been stepper motors driven by PWM circuits since the 1980's. Sorry you seem to be so far behind the curve. If you honestly believe you have an inproperly assembled harness then swap it with the other axis and see if the problem moves. Is that not the smart thing to do here if we are to compare one axis to another in the name of diagnostics?

There is a reality here that is these 2 circuits don't really care which way the power or ground comes. Only that each circuit is complete. A coil will generate an Em field no matter which side of the windings see power or ground. I think this may be what you are choking on.