Troubleshooting No Brake Lights or Turn Signals on A Trailer Towed by a 2004 Chevy Silverado  

Question:

Expert Reply:

The problem you are having sounds like just a case of finding the correct wires to connect to the correct pins on the back of the 7-Way. If your truck came with a bundle of wires above the spare tire, then the functions you need should be as follows. The yellow wire is the left turn and brake light wire, the dark green wire is the right turn and brake light wire, the brown wire is for the taillights, and the white is the ground.

On the back of the 7-Way, the yellow wire for left turn and brake should be in the 3 o'clock position. The green wire for right turn and brakes should be in the 9 o'clock position. The running light wire that seems to be working should be in the 1 o'clock position. And the white ground wire should be in the 5 o'clock position.

If the colors and functions do not match up as explained above, you will need to test the wires with a circuit tester like # PTW2993 while someone in the truck goes through the functions. Also, you will need to make sure that the ground at the trailer tongue is connected to a clean and corrosion free location. You can also check the grounds on the trailer lights. Many trailer lights ground through the mounting studs if an obvious ground wire is not present.

Finally, you can make sure that the trailer side connector and vehicle side connector are clean and corrosion free. I have included 2 FAQ articles below. The first is a more in-depth explanation on brake controller and wiring harness installation on your truck. The second shows the functions of numerous trailer connectors. Make sure the function and pin location matches, and that the function and pin location on the trailer matches that of the truck.

expert reply by: Michael H

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