Utility Trailer Brake Lights Not Working When Headlights are On, on a 2004 Chevrolet Trailblazer

Updated 12/01/2009 | Published 11/30/2009

Question:

I have a 2004 chevy trailblazer and a 5 by 8 utility trailer. I put new wiring on the trailer and all my lights work. Now, if i turn the headlights on, the lights all work except for the brake lights. When i apply the brakes, they got out and i have nothing. As soon as i let up on the brakes the taillights come back on. i have a 7 way adapter on my trailblazer and a 4 way adapter on the trailer. Any ideas?

asked by: Brandon C

Expert Reply:

It sounds to me like you have a bad ground on the trailer. You will need to make sure the white wire from the 4-Way connector on your trailer is grounded properly and then check all of the ground connections on the trailer especially where the taillights are mounted to the trailer frame. Also, if the light brackets are bolted to the trailer check to be sure they are making good ground contact to the trailer frame. If a plastic license plate holder is mounted between the left side taillight and the trailer frame this could be the problem. Once you have all of the ground connections checked, if the problem persists, you will need to use a circuit tester, item #PTW2993 if needed, to check for a broken pinched or frayed wire on the trailer somewhere.

expert reply by: Robert G