Troubleshooting Dim Trailer Lights and Running Lights and Turn Signals Blinking Together

Published 10/17/2014

Products Featured in This Question

Combination LED Trailer Tail Light - Submersible - 6 Function - 11 Diodes - Passenger Side

(1304)

$19.44

Curt Powered Tail Light Converter w/ 4-Way Flat Trailer Connector and Install Kit

(174)

$177.23

Question:

trailer has all new wiring every light has its own ground, plug is new.. When running lights are on and the blinker is on everything blinks like it is drawing power from somewhere. marker lights dim when blinker goes bright. cannot find any bleed through anywhere on the trailer.

asked by: Logan T

Expert Reply:

This sounds like a ground problem. If it only happens when the running lights are on it indicates a ground issue. Ground problems normally show up when the system is being subjected to a maximum load.

First, make sure the main ground from the trailer plug is attached to a clean and corrosion free bare metal surface. Next, go back to the lights. Most trailer lights ground through the mounting studs if there is not an obvious ground wire. In either case, the grounds have to be attached to a clean and corrosion free bare metal surface.

If your trailer has a large amount of lights then the power draw could be too much for the tow vehicle electrical system. In this scenario, you would need to use a powered converter like the 4 Pole Harness and Hardwire Kit, # C59496. The same is true if your tow vehicle has LED taillights but the trailer does not.

I have included a link to the installation details and a FAQ on Testing for a Correct Ground Connection.

expert reply by: Chris O