Troubleshooting Brake Lights of Trailer Wiring that Stopped Working

Updated 06/10/2019 | Published 06/07/2019

Products Featured in This Question

Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(17)

$52.55

Hook Probe Circuit Tester

(70)

$14.54

Question:

went over grounds and connections on both of my trailers and I still have no Brake Lts. everything else works. hooking both to my buddys truck and everything works. Hooked up a direct ground from negative post on battery to stud on the back of the tail Lt and still no Brake Lts. Is it possible to have a problem in the black converter box? thanks Scott W.

asked by: Scott W

Expert Reply:

Yes, it is possible that the converter box of your trailer wiring has an internal issue that is causing your problem.

What you will want to do is test the wires going into the box of the converter box for voltage with a circuit tester like the # PTW2993 to see if there is voltage going into the box when the taillight functions of your vehicle are applied, and then test the output side of the box to see if the current is making it through the converter. If not then the problem is that the converter box has shorted itself out and would need to be replaced.

Before you replace it you will want to inspect the wiring of your trailer to see if you can find anything that would cause the box to short out like corrosion or cut/exposed wiring. These boxes don't usually go out unless there is a short on the trailer that takes it out.

If there isn't input voltage for the converter then the problem is the wiring of the wiring kit. You will need to check to make sure it's making a solid connection to the correct circuits.

expert reply by: Jameson C