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Troubleshooting New Wiring Harness On Trailer For Reverse Lights


I am trying to wire up my trailer that is a chevy S10 bed. The wire harness on the bed is 4 wires. White/green/light green/brown. I followed the guide that came with the connector. At first, the left turn signal worked fine. But, when I use the right turn signal, both taillights flash. So, I rewired it and now my turn signals work, but I have no reverse lights. Any ideas?


Expert Reply:

In order to get the reverse lights to work on your trailer you will need a 5-way on your vehicle and also on your trailer.

It sounds like you have wired the 4-way up but now you need the reverse lights. I recommend removing the 4-way connectors on both the towing vehicle and on your trailer and installing 5-way connectors. For the trailer side I recommend part # HM47913. You would attach the white, yellow(or light green), green, and brown wires to the same color on your trailer and then run a wire from the blue wire on the connector to the backup lights on the trailer.

For the vehicle side you can use part # HM37908. This will replace the 4-way on your vehicle, and you then attach the blue wire to the reverse light circuit on the vehicle. This can be done by having someone sit in the front, apply the emergency brake and also press on the brake while you test the wires with a circuit tester like part # PTW2993. You want the wire that only shows current when the vehicle is shifted into reverse. Make sure you use caution when testing the wires. You can also chock the wheels for added safety.

I have attached links to a couple helpful articles for trailer wiring you can check out.

expert reply by:
Jeffrey L

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