Trailer Turn Signals and Brake Lights Not Working with 2011 GMC Sierra

Published 07/21/2016

Question:

Hello- I recently purchased a 2011 sierra with the factory tow package. When a trailer is plugged in I only get running lights- no brake or signal lights. I am not sure if this is new or just happened. Is there a fuse that services both of these circuits?

asked by: Tony P

Expert Reply:

Chances are the problem you're having is caused by blown fuses. There are actually two fuses that service these lights. Your truck will have a fuse for the left turn signal and left brake light and another fuse for the right turn signal and right brake light.

According to the owner's manual of your 2011 GMC Sierra the fuses are fuses 1 and 3 in your engine compartment fuse box. Replacing these will likely solve your issue.

However, being that your truck isn't that old it's more than likely that something caused the blown fuses in the first place. Of course this could have happened before you purchased it but there's no way to know that. If replacing the fuses gets your lights working you will want to inspect the wiring of the trailer to make sure there are no pinches or any other kind of damage such as a short that could cause the fuses to blow. You should also check for corrosion in your trailer connector and clean it if you find any.

expert reply by: Charles S