No Trailer Lights

I have a 2003 Excursion 7.3l Diesel.  The Stop/Turn lights are not working on the trailer.  I have checked the two fuses in the main box and both have power on both sides of the fuse.  The relays under the hood on the drivers side both click when the turn signals are on.  The 7 pin connector has power on the (+) battery charge terminal and the running lights terminal.  I checked on both sides of the 7 pin and 4 pin connector with a test light and there is no power on either side of the connectors for the turn/stop wires.  Does anyone have any suggestions on what to check now?
 
Thanks,
Tommy