Turn/Brake Trailer Lights Not Working After 4-Way Install  

Question:

Expert Reply:

Thank you for your purchase from etrailer of the # 118384 connector. There are a number of issues to check if your brake lights/turn signals on your trailer are not working, which is what I assume the results are that you were referring to. You mentioned a 4-pin tester and I'm not sure if that means a circuit tester or plug-in tester but to troubleshoot you'll need Circuit Tester # PTW2979.

Then what you'll do is take a look at your owner's manual to locate any trailer fuses or relays for the turn signals/brakes and ensure they are all there and in working order. If they are, use # PTW2979 to check the wiring going into your harness from the connector, to see if those wires are carrying the correct signals, if not then the issue is with the vehicle wiring that you'll need to figure out, but would likely be a job for a dealer or mechanic to look at.

If the signals going into your harness are okay, you'll need to test the signals coming out of the harness, and if they are correct then your issue is going to be with the trailer side wiring. You will also want to check your trailer connector for corrosion, which can be green or white in color. A build-up of corrosion can interfere with the signals getting through the connectors so if it is present you are going to need to replace the plug with # 18004.

You'll also need to make sure your grounds are attached to bare metal surfaces and free of any paint, dirt or corrosion. I have added links below to a pair of help articles on trailer wiring, including a troubleshooting guide for you to take a look at. Additionally, to help prevent any type of corrosion in your connector, and increase its durability and lifespan I highly recommend using Dielectric Grease for Electrical Connectors # 11755.

expert reply by: Kyle S

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