Marker lights and tail light does not work on right side of trailer. Don't know if back up light works on that side. All other lights work. Brown wire bad? or Ground wire issue? Grounded at each light to trailer with a connection riveted to trailer. These seem tight. Trailer is tube frame with swing away tongue. Have pulled the wiring out of the swing away tongue and examined from the 5 flat connector to where the tongue hinges and where it comes out of the frame to each light and wiring that is accessible to visual inspection seems to be in good condition. I have tested the bulbs in all 3 lights and they show continuity. Could someone point me in the right direction? Thanks!