Find where they put the ground/negative on the trailer. Pull it loose and clean both the terminal and frame. Reassemble. Then cover both with dielectric grease or vasoline. ( to stop corrosion ) Recommend you buy a 7 way truck tester to check customer wiring before renting trailer. And always test all lights/ brakes on trailer as well. Good Luck!
Find where they put the ground/negative on the trailer. Pull it loose and clean both the terminal and frame. Reassemble. Then cover both with dielectric grease or vasoline. ( to stop corrosion )
Recommend you buy a 7 way truck tester to check customer wiring before renting trailer. And always test all lights/ brakes on trailer as well. Good Luck!
Thanks so much!