Try Interior light. Again, Markers controlled by LMK are LEDS on front rear of Diesels, and Only Tender of Steam in PS-2 3V unless the board is in the engine like many PS-2 5V were. PS-2 3V steam PR and some fancy RK used a MUX to power the Engine LED Markers and they were not controlled by LMK only the tender. For the early PS-2 5V that had the HL and extra bulb for the Green marker lens, normally it was duplicate off the HL or off the Interior, possible with a Firebox if it had that. Either way, LMK would not control it, and if someone modified a SF all bets are off. Now maybe MTH did something weird with that engine, but I am not thinking so. I bet that was originally powered off an orange interior light and some one may have powered it off the ditch because the interior fet died.
Hook up a 8 pin that has the LED Markers and I bet LMK might control them. G