Trailer Running Lights Not Working When Connected to 2006 Chevrolet Silverado  

Question:

Helpful Expert Reply:

Step one in troubleshooting your trailer running lights is to isolate the problem to either the tow vehicle or the trailer wiring. You will need a circuit tester such as # PTW2979. I suggest you review the included article on troubleshooting trailer wiring as this provides a lot of useful guidance on the steps to identify the source of the problem.

Start by disconnecting the trailer from the tow vehicle. With the Silverado lights on, test the pin on the truck 4-way connector that corresponds to the brown wire using the circuit tester (and be sure the tester is grounded). Please refer to the included photo. This is the pin that carries the running light signal to your trailer. (If your truck has a 7-way connector, test the pin at the 10-o-clock position.)

If there is no signal on this pin then check for a loose white ground wire (it attaches to the vehicle chassis near the rear bumper) and for any cracked or worn insulation on the brown running light wire and apply electrical tape as needed. You can also check for a missing or blown fuse in the power distribution box under the hood.

If your tester detects a steady signal when the tow vehicle lights are on then the problem is in your trailer wiring. Again carefully check the white ground wire and brown running light wire on the trailer from the connector back to the lights. Wear spots or cracks in the insulation should be taped. Make sure the ground wire is tightly secured to a clean, rust- and grease-free unpainted part of the trailer frame. Next check the light fixtures for loose wires and look for signs of corrosion on any of the connectors or within the light housings.

Sometimes a connector that appears fine may have a slight greenish or whitish discoloration and this indicates corrosion. Any such condition should be corrected by cleaning with a fine wire brush. An application of dielectric grease on all connections (from the 4-pole to the light bulbs themselves) is recommended to keep connections free of corrosion. You can use a product such as # 11755.

expert reply by: Adam R

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