I was re wiring my boat trailer and when i was finished the left brake signal and turn signal did not work. So I checked for power first in the trialer and it did not have any and then at the truck and it did not have power. It has the factory wiring harnesses and i don't know where to start?

 

Check the fuse box under the hood. When I bought my L, one side wouldn't work. i check fuses unde the dash, all were good, just no power to the light connector. I finally found the blown fuse under the hood in the fuse box. i will bet thats where ur problem ly.