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My Trailer Lights Do Not Work Properly, How Do I Find The Problem?


Why does the right signal light stay on when the truck isn’t running? And why do the hazard lights come on when using the right signal? This is on a 2004 GMC Sierra 1500. I’ve change connection and have the same issues.


Expert Reply:

If you have a factory harness/connector, faulty wiring usually isn't the problem. I would inspect the connector on your truck # C55774 and the adapter # PK12716 connection on both sides. There is likely to be some corrosion or maybe some debris stuck in there bridging the two together. Also, I'm sure you've done this but make sure the adapter is connected to your truck in the right orientation. You can also test the pins on the connector that the harness plugs into. If the problem is there too, the cause is father into the truck's wiring.

If the adapter is the problem, we have one # PK12716 you can use for your truck and if it's your factory plug that's corroded, use this # C55774 to replace it so you don't need an adapter to haul your trailer.

expert reply by:
Adam E

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