Finalizing Final Under Hood Wiring Connections for Brake Controller on 2009 GMC Sierra


All wired in but no power


Expert Reply:

It sounds as if the final power connection needs to be made under the hood. If you take a look at the Brake Controller Installation FAQ article I have linked you to, and scroll to the bottom of the page, you can see the procedure for finalizing the connections under the hood.

The wire that provides power to the brake controller is located to the right of the power distribution box, between the box and the fender. Cut the electrical tape and free the red wire with the ring terminal on the end of it. The terminal would connect to the left hand power post. You will need an M8 nut to secure the ring terminal. Then, check the fuse diagram in your owners manual, to ensure that the fuse that activates the brake controller is in place. If not, you will need to add a 30 amp fuse.

If you want to activate the 12-volt accessory power circuit on the trailer connector, you will need to make one more connection. Find the red wire that is bundled up under the brake master cylinder. The wire will be bundled up with electrical tape, so you will need to carefully free the wire. This wire would connect to the other power post.

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expert reply by:
Mike L

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