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How To Test Wires By Function On 2003 Chevrolet Silverado 2500  


So my lovely lab when he was a puppy chewed threw my wifes on my 2003 Chevy 2500. Since then I had most of the wiring replaced by a machanic shop and now I am trying to hook up the trailer light plug back in. I got a Chevy pigtail it has all gray wiring. And when I look at schematics online my wires that are on the truck dont match up. Was wondering if I can get some assistance on this matter. Deff attaching pictures to help explain. Thanks


Expert Reply:

You can use a circuit tester like part # PTW2993 to check the wiring on your 2003 Silverado. Have someone run through the functions while you test each wire.

Then label the wires so you can attach them to the correct pins on the trailer connector. Here are the factory wiring harness colors for Chevrolet. Keep in mind the colors may vary so testing them with a circuit tester will really help.
Red - 12V power
Light Blue - Stop Light
Black - Ground
Dark Blue - Trailer Brakes
Brown - Tail Lights.

I have attached a helpful article that explains trailer wiring. In the article there are photos that identify the pins on the 7-way connector by position and function.

expert reply by:
Jeffrey L

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