Trailer lights not working when plugged in y?
My 2010 ford f150 lariay 4x4 I put new 7
pole round w 4 pin flat like factory, the 4 pin i
use for my under tailgate lights n trl, but they
only wrk w headlights on, n when i test 4 pin
w lighted 4 pin tester they blink but when i
put test light on them nothing. I put test light
on battery n chkd for ground n even w a new
spit ground down w grinder still no ground
Y?
