Brake Controller Installation Instructions on a 2003 Chevrolet Avalanche Without Factory Tow Package

Published 10/20/2011

Products Featured in This Question

10 Gauge Wire - Blue Primary - Per Foot

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Deka Jacketed 2 Wire, 10 Gauge, Brake Wire - per Foot

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Tekonsha Plug-In Wiring Adapter for Electric Brake Controllers - GM

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Hook Probe Circuit Tester

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Question:

My Avalanche has a factory 7-Way and the red power wire is attached to the power post. I inserted a green 30 amp fuse and now have power to the brake controller. Now I do not have power for the trailer brakes at the 7-Way trailer connector. The blue wire you pointed out in the photo is attached to a connector that has a blue wire coming out of it.

asked by: Craig E

Expert Reply:

Yes, we do have a photo, see link, that shows the location of the brake controller power wire and the brake controller output wire that need to be connected under the hood on your 2003 Chevrolet Avalanche if you do not have a factory 7-Way. We also have detailed instructions, see link, to help with the installation of the P3 # 90195 and wiring adapter # 3015-P brake controller on your Avalanche.

The red wire shown in the photo is the power wire for the brake controller. This wire should go on the power post closest to the firewall on the vehicle and a large 30 amp fuse should be installed in the closest location in the power distribution box.

The blue wire has a plastic connector on the end of it that you will need to cut off. This wire gets ran to the back of the vehicle and connected to the brake controller output in the 7-Way connector, # 37185. You can use an appropriate length of 10 gauge wire, # 10-1-1, to run this wire, or if you also need a 12 volt power wire at the rear of the vehicle, for your trailer, you can use an appropriate length of double bonded 10 gauge wire, # 10-2-1, and connect the white wire to the blue wire under the hood and the black wire to the forward most power post on the power distribution box.

expert reply by: Robert G

click to enlarge

Craig

10/20/2011

Bob G.

10/20/2011

Since your Avalanche has factory tow package wiring you will need to check the blue wire for output. I would start by having a helper fully apply the manual lever on the brake controller and testing the blue wire with a circuit tester, # PTW2993. First test at the back of the brake controller, then at the connection point you found under the hood. If you do not have power coming out of the brake controller there is most likely an internal problem and the brake controller will need to be replaced. If you do have power there, test under the hood. Disconnect the connector on the blue wire and test the male side for power when the brake controller manual lever is fully applied. You should have power at this connector. If not the blue wire is broken somewhere between the under dash connection and the under hood connection. This wire should be replaced with a 10 gauge wire. If you have power at the under hood connector and the 7-Way at the rear of the truck is not working, the wire is most likely broken somewhere going back to the 7-Way. The best solution would be to remove the male connector and bypass the factory wire with a 10 gauge wire. At the back of the factory 7-Way, sever the brake output wire, see trailer wiring diagrams link, and attach the new wire there also. You will then have power when the manual override is activated and when the brake pedal is pressed.