Troubleshooting Dim Turn Signals on Trailer with Running Lights On

Updated 05/21/2018 | Published 05/18/2018

Question:

Turn signals dim when running lights are on. To the point that turn signal is barley noticeable. Would a heavy duty turn signal help?

asked by: Richard S

Helpful Expert Reply:

I am not sure what vehicle you have, or the particular wiring harness you have installed, but most likely a heavy duty flasher is not necessary for the turn signals to properly illuminate on the trailer. What you are describing sounds like a possible weak or bad ground somewhere on the vehicle or trailer wiring. A weak ground will often allow some lighting functions to work, but when an additional lighting function is activated (such as turn signals with the running lights already on, in your case), there is simply not enough power to go around.

I recommend checking the main ground on both the vehicle side and trailer side connectors. Make sure the ground wires are securely attached to clean, bare metal surfaces that are free of any dirt, paint, or corrosion. You can also make sure the trailer tail lights themselves are securely grounded, whether through their mounting hardware or with a dedicated ground wire, depending on their particular design.

If this does not resolve the issue, please let me know the year, make, and model of your vehicle, along with the model harness you are using, and I will be happy to look into this further.

expert reply by: Chris R