Lionel Fastrack Remote Toggle Switch Issue

Some notes:

Fastrack switches and the remote controller has 1 wire called RSC Lights- this is the status wire of the direction indicator. It is a plus 5V or minus 5V in reference to GND or Common- aka outside rail.  Again, this Yellow wire or RSC Lights is what would power the red and green LED indicators of the remote switch controller

The Thru (green wire) and Out (red wire) are the control wires for switch direction. They get shorted to ground or common one at a time to switch direction. One note- these terminals and contacts are also in parallel to the anti-derail sensing sections of outside rail on the switch. Just saying, car wheels can also ground them.

Black is common or ground- and key- is the reference for the DC ground return path for LEDs

Hoping you did not somehow miswire or damage the RSC Lights output.

Check your wire in the RSC terminal. You may have the wires insulation in the way. Also, do a continuity check with an ohm meter of the wire end to end. It should read zero. Anything else is bad.