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Troubleshooting 7-Way Installation that Has No Right Turn or Stop Lights on Trailer  


When we hook up the 7-way plug on our camping trailer to the car, the right brake light and right turn signal on the trailer does not work. After driving 10 or 15 minutes they are both working and continue to do so for the rest of the trip. Next time we hook up the same thing happens. We have determined the problem is on the side of the car.


Expert Reply:

It sounds like you may have a loose wiring connection or a corrosion problem on the 7-way pin for the right turn/brake lights. This pin is the one at the 3-o-clock position as you're looking at the vehicle's 7-way; please refer to the linked photo.

Check that the (usually green) wire that runs to this pin is securely affixed to the 7-way and check its insulation for any signs of wear marks or cracks that could be causing an intermittent short, especially at spots where it may rub against the trailer frame. Also check that both the vehicle socket and the trailer plug contact surfaces are free of corrosion inside and out; even slight greenish or whitish discoloration can indicate corrosion that is bad enough to cause an issue.

You can also test the vehicle socket with a circuit tester like # PTW2993 (when the trailer is not connected) to see if the correct right turn/stop signals are present at the 7-way.

Please feel free to let me know your vehicle year/make/model/version and I will find you a correct replacement wiring harness. If you have a vehicle with a U.S. Car connector and if the issue is the 7-way socket itself then you can use the Pollak replacement 7-way # PK11893 that you referenced.

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