Hi All. I opened this TMCC engine #6-18287 up the other day thinking I would upgrade all lighting to leds; they are now all GOW bulbs. The connections from frame to shell are 4 spring connectors as shown below. The bulbs all appear to run on track voltage. The headlights/ditch lights and backup lights are sensible enough.
But the front and rear number boards only run on DC power applied as shown. There is a tiny pcb tucked down behind the plastic bulkhead with the screw holes, just to the right of the spring connector block. It looks like it might have a couple of diodes mounted. Does anyone know just how this shell wiring works and how it is controlled? The big rats nest of wiring below the connector block is all white wires only, so tracing it looks like a waste of time.
The mobo is 691-PCB1-11E, pretty straight run of the mill stuff. There are connections to the headlight and rear light board mobo pins, but no other lighting connections I can see. Any help or ideas appreciated. 
Rod
