Not suppose to be posting those diagrams John.
The PS-2 board always has one of the motor leads hot at PV. Yel in fwd, wht in reverse. The board FET controls return to ground for motor control.
So with 2 diodes, one on each motor lead, the MUX now has PV available. Yes the Head Light wire in 10 pin becomes the MUX engine signal.
Be careful what you do with tach. The blue PCB return goes through a 181 ohm current limiting resistor on the PS-2 board when using 7 pin connector only. If you use one of the other PCB grounds, you smoke the Tach reader immediately.
The MUX has the resistor for the blue tach wire. This is why no speed control when you try to run an engine with the shell off and the ten pin from shell to chassis unplugged. Orange is pass thru. Gray 5V is common and ok.
This is also why if your swapping tenders of dissimilar wiring, you can smoke the tach reader, or worse for some engines. G
