Troubleshooting Trailer Wiring Where Running Lights Stop Working

Updated 02/04/2019 | Published 02/02/2019

Products Featured in This Question

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

(329)

$63.45

Hook Probe Circuit Tester

(65)

$13.35

Question:

Hello, I recently purchased and installed your harness and tester on my 2017 Nissan Rouge. Everything worked as should with the tester. Yesterday, I bought a trailer, checked all the lights, and all work as should. The next day, turn and brake lights work, but not the running lights. I disconnected from the trailer and installed the harness tester. Turn and brakes lights work fine. And when I turn on the headlights, the light on the tester for the running lights will blink on and then stay off. All the lights work on the Nissan. What could this be? Thx,

asked by: Rick D

Expert Reply:

Sounds like an intermittent connection to the running light circuit on the trailer wiring harness or the converter box is bad. I'd recommend using a circuit tester like part # PTW2993 to test the circuit that feeds the running light wire on the converter box as well to see if you see the same blinking. If so, then the box is fine and it's most likely a connection issue. If the circuit is fine there then the converter box has shorted out.

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.

expert reply by: Jameson C