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No Plate or Running Lights but Brake and Turn Signal Work on New LED lights


Have new truck 2021 silverado. Replaced trailer lights with new LED lights, worked great. Broke housing on left side so replaced with new LED again and everything works except the running and plate light. Filed mounting holes and ground wire mount. Wiring looks fine under trailer from 4 flat plug all the way back. Ground wire was pulled free at tounge of trailer repaired the connection and still no running light or plate illumination light BUT turn and brake work fine. Checked all fuses and relays and they are fine. Im lost please help


Expert Reply:

I recommend using a Probe Circuit Tester # PTW2991 to test the entire circuit. This type of tester will help you to identify both power and ground connections and that they are properly working. I have also included a link below that will help you to identify different wiring connections and where to check.

I would begin by checking the power at the 4-way connection. Be sure to check it on both sides of the connector as there may have been a break inside the connector. From there you can test power at the light. This will confirm that the wiring wasn't damaged. If you have power at both sides of the plug and not the lights you may have a pinched wire that is going to ground or even broken wire in the system.

You can also use this tester to check your ground circuits to ensure they are making it all the way back to the battery. Make sure to follow the ground connection all the way through circuit from truck to taillight similar to the way you tested the power circuit.

If all the wiring tested fine please let me know and I can help you through some other tests you can do to make sure the lights aren't defective.

expert reply by:
Gregory M

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