Extra Blue Wire Near 7-Way Trailer Connector on 2003 Chevy Silverado 2500 HD

Updated 05/04/2026 | Published 05/26/2019

Question:

I have a 2003 Chevy Silverado 2500 HD gas truck. My new puppy chewed the wires behind the trailer wiring plug. I know where all the wires go into the plug, but there was a blue wire by itself. I cannot find where it goes. It has a piece of a plug on the end of it. I’ve looked up on the frame to see where it went. Can’t find anything. Can you help me ? Thanks I just sent my question with a picture. The lone blue wire does not go to that plug. It has to go somewhere else. Thanks again

asked by: Jessey B

Expert Reply:

I'm pretty sure that's to wire up a third brake light on a camper shell. To know for sure, take a circuit tester, like our part # PTW2993, and test that wire while applying the truck's brakes. If I'm correct it's a dedicated brake light wire and it doesn't need to be connected to anything unless you have a camper shell with a third brake light, you need to connect to it. Without the shell it's an extra unused wire.

expert reply by: Charles S