Trailer Brake Lights Do Not Work After Installing Curt Trailer Wiring Harness # 56049

Updated 09/23/2013 | Published 09/20/2013

Products Featured in This Question

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

(88)

$43.89

Hook Probe Circuit Tester

(60)

$13.33

Question:

Hi Back in March I ordered part # C56049. I went to plug it in to my trailer and only got parking lights and blinkers.brakes lights only work when i unplug and plug them back in -this is done with the brake pedal down.ground wire goes from the plug to the lights. could the part be bad.

asked by: Ken V

Expert Reply:

It sounds like a bad ground connection. What you will do is disconnect the trailer from the vehicle. Then make sure the ground for the wiring harness # C56049 is attached to a clean and corrosion free bare metal surface. Use a circuit tester like # PTW2993 if you do not already have one to test the pins on the 4-Way while someone sits in the vehicle and goes through all the lighting functions.

If the brake lights/turn signals still do not work use hte circuit tester to test the wires going into the converter box. If the signals are going in but not coming out that does indicate a problem with the converter and harness will need to be replaced. If the signals are not correct going into the box then the issue is on the vehicle and will need to be tracked down. It could possibly be a blown stop light fuse.

If everything checks out fine on the vehicle then the issue must be on the trailer. Make sure the trailer connectors are clean and free of corrosion. Make sure that the main trailer connector ground and the grounds for all of the lights are attached to clean and corrosion free bare metal surfaces. And inspect the trailer wiring for any exposed copper strands that may be touching bare metal.

Also if the trailer has an aluminum frame, tilting bed or folding tongue then running jumper grounds from the lights to the main trailer connector ground should help. I have included a video and FAQ links that will help you to troubleshoot.

expert reply by: Michael H