Troubleshooting Trailer Lighting That Blinks when Headlights are On

Published 11/21/2018

Question:

I have a Haulmark trailer. The lights blink when the vehicle headlights are on. They stop blinking when the brake is applied. They do not blink when the headlights are turned off. I am not sure what is going on here.

asked by: Eric

Expert Reply:

Since all the lights are blinking and it's only happening when the headlights are on the issue has to be related to the running light circuit of your trailer wiring. Most likely you have an intermittent connection here due to corrosion on the trailer wiring connectors and cleaning them will take care of the problem. The other possibility is that you have a weak ground on your trailer wiring. An insufficient ground can sometimes cause unexplainable behavior on trailer taillights. You would want to improve the connection of the main ground wire on your trailer wiring or even run a ground wire from each assembly to the ground of the connector.

expert reply by: Jameson C