Left Turn Signal Not Working on Trailer

Question:

no juice on trailer plug in left turn signal but brakes and running lites work /

asked by: Dick B

Expert Reply:

To determine the cause of the left turn signal not working on your trailer, I first recommend checking the vehicle side connector. You can use a circuit tester like # PTW2993 to test the functions on the connector with the trailer disconnected. Have somebody sit in the vehicle and operate the light functions while you do this.

If the left turn signal does not work at the 4-Way connector, then you will want to test the yellow wire leading into the converter box from the vehicle. If it does not have a signal going in, then fuse or splice is bad. If it does, then check ground and test rear 4 way. replace harness if needed after that.

If everything checks out fine, I recommend going to the trailer side and ensuring that all ground connections are made to clean, bare metal surfaces on the trailer frame. Check to make sure there is no debris or corrosion that may be preventing a solid connection. When only one function is not working correctly on the trailer lights, the cause is often a weak or bad ground.

Also make sure both the vehicle and trailer side connectors are free if dirt and corrosion. Simply clean out as needed.

I have included a troubleshooting article that you might find helpful. If you are still unable to find the cause, please let me know and I will be happy to help you further.

expert reply by: Chris R