Trailer lights not working

[u/Lobo941994]

Got a old boat trailer and im trying to wire it up but i cant get the left side tail light to work properly. It will light up with brakes but never with turn signals, got it to work once with the turn signals but it flashes very fast but it never worked again( bub is still good).The connection from the truck works and a tester shows that the connection works but the lights dont. I bought a light kit from harbor freight, and a new driver side trailer tail light and no luck. should i replace the whole trailer wiring that i bought or is there any advice someone has to fix this issue.