Trailer Lights Do Not Work When Vehicle Headlights Are Turned on

Updated 06/21/2017 | Published 06/20/2017

Question:

I have a two wheel trailer, all the lights work on the trailer except when you turn the headlights on in the car the back two taillights on the trailer dont come on. The two side markers light up and all the other lights work, break lights, turn signals.

asked by: John S

Expert Reply:

The issue you are having with the tail lights on your trailer are most likely due to a bad ground. Other lights like turn and brake lights will only draw power when the functions are used but tail lights draw more power and that is when the problem comes up.

Inspect the ground on your trailer connector and make sure it is secured to clean bare metal. Check the lights also to see if they are grounded from the main trailer ground or through their mounting hardware. Clean any corrosion or rust found.

Also, if you have added additional lights on your trailer, they could be drawing more current, causing the problem. I have attached a link to a helpful article for troubleshooting you can check out.

expert reply by: Jeffrey L