Where Do the Red and Blue Wires Connect Under the Hood on a 2003 Chevy Silverado

Updated 04/22/2010 | Published 04/21/2010

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Question:

In the fuse box under hood the red and blue wires are come off of what? Where do they lead to? Because i have a 7 way connector on the back of my truck by the spare tire on the wire harness. Thanks

asked by: Brad h

Expert Reply:

The red and blue wires under the hood of your 2003 Chevy Silverado come from the factory wiring in an electrical junction box to the left of the brake pedal to connect to a brake controller.

You will need to wire the red and blue wires so your brake controller will work. First, place the red wire over the closest positive post (back left if facing the truck from the front) on the fuse block. A 20 or 30 amp fuse (see the brake controller instructions for which size to use) is needed in the empty slot nearest the positive post to power the brake controller.

Next, clip off the connector on the blue wire and connect it to a wire that you have run to the electric brake wire coming off the back side of your 7-Way plug in the rear of the truck. If you also need power run to the 7-Way connector, you can run a wire underneath the hood to the other auxiliary power post near the fuse block. You would then install a 20 amp fuse in the slot closest to this power post. I recommend using the jacketed 2 wire, # 10-2-1, for this application. If the second auxiliary power post is already in use, you could also just run the power wire to the positive battery terminal and install a 40 amp circuit breaker, part # PK54540, if needed. If you used the white wire from the # 10-2-1 for your blue wire under the hood, you could use the black wire to run your power lead. I have included a link below that shows images and more instructions for wiring your Silverado.

expert reply by: Michael H