GGG posted:PS-2 and PS-3 would be different method since one operated 6V bulbs for Lights and a separate circuit for Markers. PS-3 is all LEDs. MTH does this with flash coding and a secondary PCB to do bi-directional on GG-1s. G
For directional markers on PS/2, I'd just wire to the headlight circuit as I've previously stated. For PS/3, unless you have the directional marker code native, you can do essentially the same thing.
Here's my comment about PS/2 directional markers. I don't see any reason this wouldn't solve the directional marker problem without any special code or PCB.
I believe that could be accomplished by using some common anode three-wire RED/GREEN LED's and two 330 ohm resistors. Wire the anode (center lead) to PV and the negative leads to the forward and reverse light circuit.
As for PS/3, a similar technique would appear to work just using the headlight circuit as well.
For PS/3 you need common cathode 3-terminal LED's. The common cathode goes to PCB Ground and the anodes go through a 100 ohm resistor to the front and rear headlight outputs. The reason for the resistors is to prevent the bi-color LED's from starving the higher operating voltage headlights and not allowing them to function.
I'm all ears if you think there's some flaw in this logic. 
Previously, you stated that the PS/3 could drive multiple LED's on a single light output.
