Troubleshooting Dim Trailer Tail Lights When Running Lights Are On

Updated 12/05/2022 | Published 12/04/2022

Products Featured in This Question

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

(23)

$80.47

Hook Probe Circuit Tester

(70)

$13.94

LED Combination Trailer Tail Lights - Submersible - Driver and Passenger Side - 25' Wire Harness

(3511)

$80.47

Question:

I have the trailer harness C56303 installed and I am using the lights TLL16RK. It seems to work fine if the car is off and I put on the hazards. But if I turn on the car, the headlights are on automatically and then the trailer lights blink very dimly. I thought maybe it was wiring, but I have tried to test those and it seems consistent that if the car has been sitting and I attach the trailer and turn on just the flashers, they work fine. Could there be some mode that the box is getting into that is causing the lights to be dim? Or is it probably some short or bad connection in some wire that isnt used for the flashers?

asked by: Nick R

Expert Reply:

Anytime someone mentions the turn signals and brake lights are dim when the running lights are on I always verify the lights are connected correctly. You will want to ensure the running lights are connected to the dimmer running light on the trailer. You can also verify the functions on the vehicle 4-way as well as at the trailer. A Test Light # PTW2993 will help you determine if the wiring is crossed or shorting out to another circuit. This will allow you to also verify the input and output wires on the Curt T-Connector Vehicle Wiring Harness # C56303 are functioning correctly. Be sure to also check the connections at the LED Combination Trailer Tail Lights # TLL16RK as well as ensuring you have a good clean ground connection at the tail lights and the frame connector near the 4-way.

expert reply by: Bud M