Left Signal on Trailer Flashes when I Indicate Right Turn

Updated 06/16/2014 | Published 06/13/2014

Question:

I have a 96foot LX450. When I signal a left turn all works as it should. When I signal right, the lights on the right side passenger side of the trailer go out and the left turn signal blinks on the trailer. All the lights work properly on the vehicle. I tested the circuits from the vehicle harness and would get no current when indicating a right turn. Ground or is the green wire bad? All I see is the wires behind the bumper....how far and where do I trace the green wire to, if you think that may be the problem?

asked by: Jake D

Expert Reply:

It sounds to me like you may have a ground problem. A weak ground can cause your signals to malfunction so you will want to check and make sure that the ground wire on the vehicle, as well as the trailer, is secured tightly to a clean metal surface. I also recommend checking the trailer connectors for corrosion.

If you are still having problems and your 1997 Lexus LX 450 has an aftermarket wiring harness with converter, I recommend using a circuit tester like # PTW2993 to check the functioning of the green wire. If you tested the pin for the right turn signal and received no current, I would then test the wire behind the connector. If you receive current, then I think it is safe to say that there is something wrong with the connector. If you do not have current, I would move on to testing the green wire going into the converter box.

If you test the green wire going into the converter box and you do not have current, I would trace the green wire as far back as possible to see if it has been damaged, pinched, or if the connection to the vehicle's taillight wiring has come apart. If you do have current, it sounds like we are dealing with a bad converter box and the wiring harness would need to be replaced.

The most common cause of converter box failure is due to a short somewhere on the trailer. If you have a bad converter box, you will want to check all of the wires on your trailer to make sure that all are intact and undamaged otherwise this could cause a failure in your new converter box.

If you have a wiring harness from the factory, I do not have any information for those and recommend contacting a Lexus service center to help you with this problem.

expert reply by: Leah S