The red fender tail lights are not working on our 8400. I am not so worried about the tractor, but this also affects pin #6 (brown wire)  on the 7 pin connector which powers the tail lights on the grain cart. I jumpered power to the pin and my red lights on the tractor lit up as well as the flashers on the cab, so the wiring at the connector is intact.  I checked all the fuses I could find associated with the lights and all were ok.  Where could I be losing power to this circuit?