Brake and Turn Signal Lights Cut Off with Headlights On

Updated 09/30/2019 | Published 09/28/2019

Question:

I have an 05 f150 when i turn on my headlight or parking lights i have no turn or brake lights whith headlights off everything works fine

asked by: Ronald P

Expert Reply:

The issue you are having with your running lights and brake/turn signals is going to be caused by a poor ground. The poor ground could be either on the vehicle side or trailer side. I recommend that you first re-ground the vehicle side trailer connector. If this does not fix your issue then re-ground the trailer side trailer connector. If this still does not fix your issue then run a ground wire from each light up to the main trailer ground. This issue comes up often and it is almost always an issue with a poor ground.

expert reply by: Conner L