Troubleshooting Trailer Connector And Wiring On 2012 Chevrolet Colorado

Updated 11/10/2015 | Published 11/09/2015

Products Featured in This Question

Hook Probe Circuit Tester

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T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

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Question:

I have a 2012 Chevy Colorado and had UHAUL install a 7-way connector for a travel trailer. Everything works correctly except the brake lights dont work on the trailer. I understand that my truck has separate wires for the brake lights and turn signals. Im told I need some type of a splitter box but dont know what I need. I have a brake controller because my travel trailer has electric brakes so Im not sure if the brake light wire would connect to the same connection as the brake controller wire.

asked by: Larry L

Expert Reply:

When a 7-way connector was installed on your Colorado, a converter should have been included because the vehicle has separate lighting meaning the brake signal and turn signals are sent along separate wires. It sounds like the wiring kit was not installed correctly.

For your 2012 Colorado, I recommend a wiring harness like part # 118301. This harness plugs into the truck wiring under the truck bed on the driver side.

I recommend using a circuit tester like part # PTW2993 and test the 7-way connector pins for function. If you are not receiving the brake signal from the appropriate plug, I recommend returning to the installers and have them correct the installation.

You should follow the wiring from the connector back to the truck and see if a converter is wired in place. Test the green, yellow, and red wires coming out of the converter box to see if they show current when the brake pedal is pressed.

If the wires from the converter and the pins on the connector are receiving the signal, you will need to use a 12V power source like a car battery and test the trailer connector as well. Attach the ground wire from the trailer connector to the negative post and use a circuit tester as a type of jumper from the positive post to the wires or pins on the connector. Look for any loose or damaged wires on the trailer and also check for any signs of corrosion on any of the pins.

I have attached a link to a helpful article about trailer wiring you can check out. In the article it has wiring diagrams and also shows how a vehicle side and trailer side plug should be wired.