All Trailer Lights Work Except Brake Lights Using Tail Light Kit # TL29BK

Updated 05/23/2013 | Published 05/21/2013

Products Featured in This Question

Standard Trailer Light Kit with 25' Wire Harness

(452)

$28.35

Trailer License Plate Mount Bracket, Heavy Duty Zinc Steel

(430)

$8.11

Hook Probe Circuit Tester

(60)

$13.03

Question:

All lights work except when i apply the brakes ?

asked by: Rick

Expert Reply:

This is most likely a bad ground. Ground issues normally show up when there is more load on a circuit such as the constant draw of brake lights. There are a few things that could cause this to happen. The first thing you are going to want to check though is the vehicle side connector to make sure the brake signal is reaching that point.

Use a circuit tester like # PTW2993 if you do not already have one to test the vehicle side connector. If the brake signal is not coming through, then check the stop light/CHMSL fuse. A blown fuse could cause this issue.

If the vehicle tests out ok, then the issue must be on the trailer. Make sure the trailer connectors are clean and free of corrosion. The main trailer connector ground and all the grounds for the lights need to be attached to clean and corrosion free bare metal surfaces.

Lights that ground through the mounting studs can sometimes run into ground problems when there is a plastic license plate bracket between the light and the trailer. Switching to a metal bracket, like # LP15SB, would solve this issue. Or you could run a jumper ground wire from the stud (between the light and plastic bracket) to the trailer frame.

If the trailer has an aluminum frame, a tilt bed, or folding tongue then it will help to run jumper grounds from the lights to the main trailer connector ground.

expert reply by: Michael H