MTH DCS Standard Gauge Lighting Failure.

PS-2 or PS-3?  First test the continuity of the wires from board to connector.  Broken solder joint under heat shrink at connector a possibility.  Then is the bulb a screw in type?  I have seen the isolated socket not make good contact with bulb center.  I have on occasion had to add a blob of solder to the socket center, or even the bulb.  Just remember for PS-2 bulbs are isolated from the frame ground.  G

Thanks GGG.  It is PS2.  I removed modular plug.  Applying 12 v AC to front assembly, on the bench,  allows the light to light normally.  So bulb/socket is good.  When I put a multimeter on the two leads coming out of the engine there is no voltage and no voltage change when I hit "headlight on" on handheld.  I assume the next move is to get her to you or even open her up here and inspect.  All other functions are normal.

If you are sure wires are all good, I would just need the circuit board.  Probably a light fet failed.  Instead of looking for voltage with engine NOT powered, put voltmeter on headlight wire connector (blue normally) at 12 pin connector and other at the molex connector pin and check continuity.  Is it 0 ohm resistance?  then test purple PV wire.  If one or the other is high ohm you have a break somewhere in between.  G