LED turn signal flash like 4 ways  

Question:

Helpful Expert Reply:

I'm sorry to hear you are having trouble with your new LED trailer lights. There are several issues that can cause odd combinations of trailer light functions to work or fail. It sounds like you already have a circuit tester like # PTW2992, so troubleshooting should be a breeze.

The typical culprit when both lights blink is a ground issue somewhere on the trailer. It may not have been obvious with the incandescent bulbs because they require more power to function than your new LED bulbs. Since LED bulbs use only a fraction of power to function, any power issue could trigger other lights to function.

To troubleshoot this issue, start at the trailer connector. Check the connector for any bent pins or corrosion and verify that it is grounded to a clean bare metal surface on the trailer frame. Replace the connector if needed.

Next, inspect the stop, turn and tail light circuits on the trailer. Look for any damaged or frayed sections of wire that could allow two circuits to touch. repair or replace wiring as needed.

Finally, check the tail light assemblies themselves. Trailer lights like # STL8RB ground through the mounting hardware, so you will need to make sure that the light mounting area is clean and paint-free, and that the surface is not made of aluminum. If the mounting surface is made of aluminum, connect a wire to the light stud and ground it to the trailer frame. You can also run a ground wire from your lights right up to the trailer connector to see if the ground is the issue.

If ground area is already clean, disconnect the ground wire and attach it to a long piece of wire. Run this wire to the vehicle's negative battery terminal for testing purposes.

If this solves the issue, the ground wire can be permanently run to the negative battery terminal or moved to a new location with a verified connection to ground.

I've attached a link to the installation video for the # STL8RB trailer light and a video on troubleshooting a ground connection for your convenience.

If you've already completed these steps and have not come to a resolution, there is one more thing you can try. You'll need to disconnect the new tail lights and test the trailer wires that feed into those lights using the circuit tester. Hook the trailer up to your vehicle and have someone turn on the left blinker. Then test the left and right turn wires to see if both lights are being triggered. Repeat this on the right side. This will tell you if there is wiring issue somewhere else on the trailer allowing power to feed on both circuits. If this test does not show power feeding on both circuits then you'll know it is a problem with the new lights and they will need to be replaced. If they were purchased recently they probably still under warranty.

expert reply by: Amy W

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