Trailer Lights Go Out When Brakes are Applied

Updated 02/26/2010 | Published 02/25/2010

Products Featured in This Question

20 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 30" Ground

(337)

$18.81

Battery Post and Terminal Cleaner - Wire Brush

(15)

$4.72

Question:

All the trailer lights work until the brake petal is pressed. When braking all of the trailer lights go out. I have moved the ground wire to make sure there is no connection problem and it still does the same thing.

asked by: Ron

Expert Reply:

It sounds like you do have a ground problem. You might want to check where your lights are mounted. If they are bolted on there could be some corrosion between the mounting bracket and the trailer or the bracket and the light. If this is the case you will have to clean out any corrosion you find. We have a wire brush Battery Post and Terminal Cleaner - Wire Brush # DW00254 that could be used in the cleaning process.

There may be a ground loss if there is a plastic license plate bracket mounted between the left side trailer light and the mounting bracket.

Another possibility is if your lights are welded on, there could be a crack that is allowing rust and corrosion to affect the ground between the trailer frame and the light bracket.

You can also continue to try moving the ground wire to see if any location finally ends up working.

expert reply by: Michael H