Should Blue Wire on Trailer Have Power

Question:

Should the blue wire in the main pigtail should I have juice

asked by: Freddie O

Expert Reply:

The blue wire on a trailer is typically the output wire to the electric brake assemblies. If this is the case on your trailer then the wire should only have power when you are hooked up to the tow vehicle and are applying the brakes, either by pushing on the brake pedal or by using the manual override lever on the brake controller.

Since trailer wiring colors aren't always consistent I do recommend verifying that this is the function of your blue wire. You can simply follow the wire along the trailer to see where it goes or simply test it by applying 12V power to see what function it activates.