Lionel O72 Fastrack switch controller

The yellow wire/pin at your connection measured to the black wire/pin connection should go from + to - 5VDC when thrown.   If not      then I would suspect the circuit board.  

Just getting back to basics - have you confirmed that the four small wires in the black controller wire are all connected tightly and in the proper order in the switch posts and, conversely, taken the controller apart and confirmed that the four wires are also connected tightly and in the correct order in the controller ?

Thanks for your responses.  There is no voltage reading between yellow wire and black wire when the controller lever is moved.  Controller wiring appears to be correct.  I connected a controller used with a working turnout and got the same result that was obtained with the original controller.

This still may not be board issue.   Could be a pinched wire internal to the Switch.  The microswitches that detect the position of the Switch provide the input to the board change the polarity of the 5VDC to the LED controller lights.  Use your VOM and sniff out those microswitches to confirm there is a voltage at both of them.

Appreciate your input.   Tested with nominal 15 volts setting at transformer.   When micro switches are positioned so switch lever arm is not contacted by sector gear, I measure 14.8 volts at red wire, 14.8 volts at yellow wire, and 4.8 volts at blue wire.  When micro switches are positioned so lever arm is depressed by sector gear, I measure 14.8 volts at red, blue, and yellow wires.  I measure same respective voltages at the pins on circuit board that appear to connect with sockets.  All voltage measurements vary by a few tenths of a volt.

Must be the board.