2003 Sierra towing electrical question

Our new 2003 Sierra has the towing package with 7pin connector. I added brake control via plug in harness with no problem. The charging (or aux hot) lead to trailer is not hot at rear plug. Do I need to run the lead or is it
there waiting for a fuse? Any help would be appreciated or I'll have to have dealer look at it.
Thanks,
Mel
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Just one question: Are you checking at the plug itself or at the end of the harness that plugs into the plug? If you are checking at the end of a harness you probably have the wrong harness. The 03 harness is unique from the 99-02 harnesses. They all look alike but the wiring is different. That is the reason for my question. If you are checking at the plug itself, I don't have the answer for you.
Jerry H.

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I am checking at the plug at rear bumper. Harness supplied with brake control was correct 2003 harness and brakes work fine. Instructions with brake control (none came with harness) do not address the hot lead. I am not hot on the aux lead at bumper. I would not be surprised to learn that I need to add a fuse but don't know where in under hood box it would go.
Mel

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And no, you don't need to run another wire.
Jerry H.

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have
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I have a 2003 Silverado Z71 I had the same problem. You need to put a fuse under the hood in the fuse box. Mine was the top left fuse. The factory put a fake red solid dummy fuse in it and after I replaced it it I had power at the rear plug.
Hope this helps.

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Bingo, the only thing this post needs is the amp rating. The fuse is supposed to be 40A or so I read (I haven't installed mine yet, so I'm going on what I read on rv.net forums)
Good Luck
Tony

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Thanks for the help everyone.
The red dummy fuse was right where Mike said it would be. I'm readt to travel.
Mel

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aux
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to
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