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Thread: diagnostic port

  1. #1

    Default diagnostic port

    hey i bought a 2003 gmc sierra a couple months back and my check engine light recently came on so i went to hook it up to a code reader and it never worked. so i got looking at my port and theres only 4 wires going to it. it s got a purple wire in port 2 a black one in port 4 a black one with a white stripe in port 5 and an orange one in port 16. i dont know wat i should do cuz cant get a hold of original owner to ask him wat he was doing and hes got all sorts of strange wiring down there thanks for the help in advance

  2. #2
    Jr. Engineer hundojoe's Avatar
    Join Date
    Feb 2010
    Elk River, Minnesota


    I know this will seem strange but does your cigerette lighter work? If it dosent work there is a fuse under the hood that ALDL port and cigerette lighter are powered by, had same problem when I tried to hook up my hypertech tuner. Changed fuse and life is good.
    Last edited by hundojoe; 07-08-2010 at 03:10 PM.

  3. #3


    I am having the same problem. The lighter has never worked and now I need to replace my fuse again. How can I disconnect/replace the lighter?

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