Bob, No it still is not standard, because all the variations I mentioned come in to play. BUT yes, PS-2 3V tend to be more standard because all PS-2 3V steam have the board in the tender except things like standard gauge and #1 gauge. The main difference between PS-2 3V steam with MUX and without is the use of the purple wire on Pin 1. It is a Headlight or Interior wire on Non Mux and it is a MUX signal wire on MUX versions.
There are variables though. For example switchers with a forward coupler usually do not have a pickup roller and therefor the Red is repurposed as forward coupler.
As far as lights go, on simpler RK a Headlight, fire box and cab light may all be on one circuit (Headlight) or if MUX board involved one circuit can control two outputs. In that case HL is separate and Cab light and firebox are together. ONLY 10 wires available.
Wht and Yel for Motor, gray and green for smoke fan, Brown and purple for Smoke heat, Red and Black for AC power, Gray, blue and orange for Tach, purple and blue for Head Light. Gray is doubled up and so is purple. Doing the math that is 11 wires required. That is why purple PV is generated from motor lead via diode under the engine PCB or directly from diodes on motor or even smoke unit on some models (Ten Wheeler). That way only ten wires needed. G
