Thanks to both of you I understand the problem !! Now I just have to get out the soldering iron and fix it....
Bill

On my ON30 layout I have a reversing loop and I have insulated the loop with plastic insulators. As a further description the insulated track section is between two facing turnouts. I have a DCC Forney and a DCC 4-4-0. The problem I am having is that the loco causes a short (the leds blink) when it crosses the point at which the track is insulated. I have tried to run the engines at full speed to see ifv they could coast over the insulation joint without success. I have tried cutting the gap wider to see if the short is avoided without success. It appears the trailing (or leading) wheels are causing the short but  I am not sure. Help!!
Bill Waggener