How to wire the lionel 6-2117 target signal

Use an insulated track section. Take one outside rail out of the metal ties using a screwdriver. Put a piece of insulating material into the ties and put the rail back in place. This will insulate it from the rest of the track. Put an insulating pin in the just insulated rail. connect your signal ground to the insulated section and power to the bulb terminal. When your train moves onto the insulated section, it will light. If you want reg/green indication use a relay to switch the colors. Good luck.

"use a relay to switch colors"..., can you explain how this is done or wired?

 Wire hot / power to the relay center contact.  Run the power lead for green lamp to the normally closed contact and the power lead for the red lamp to the normally open contact.  Run power to one lead of the relay coil.  Connect the other coil lead to the insulated rail.  Connect the common to the block signal as usual.

When there is no train in the end of track block the relay coil is not energized and power flows through the normally closed contact to the green lamp(when your siding is switched "on").  When the train enters the end of block insulated section, the wheels complete the power circuit to the coil energizing the relay and pulling the normally open contacts closed, thereby switching power to the red lamp.

Explained here

http://www.jcstudiosinc.com/Bl...=410&categoryId=

Dale H