another trailer question-wiring

[mx547]

which wire is the runner lights on a four-flat plug? the trailer end is one female, three males. the runners have quit working. i still have brake lights and turn signals. for awhile, i could just position the wire a certain way to get it to work so i know it's just a bad connection.

 

[BSWIFT]

White, green, yellow, and brown. White is ground, green leff, yellow right, brown is brake and running lights.