The brake and turn signal do not work on one side of the trailer. I bought the tester thing at BPS and they are all good to the back of the truck.... when I plug in the trailer the one side goes out. I tried switching the lights on the back to see if the light was not working but the other side does not work either when plugged into the bad side...
The parking lights work... just no brake or turn signal.
What can I look for to try and fix