Troubleshooting a Converter Box When a Trailer Blinker is Not Working

Updated 07/18/2019 | Published 07/14/2019

Products Featured in This Question

Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(207)

$72.73

Cordless Circuit Tester

(15)

$19.26

Question:

Hello, I had the C56106 installed on our 2012 Toyota Sienna so we could tow a 4 pin kayak trailer when we bought the Sienna in 2012. The last time we took our kayak trailer out we had issues with the driver’s side blinker not working correctly on the trailer works fine on our Sienna. The brake lights work on the trailer, but the right passenger side is brighter than the left. I replaced the trailer’s left light bulb but that did not correct the issue. I thought it might just be an issue with the trailer wiring, but I recently purchased an C57674 from you so we could two a small T@B trailer. I noticed the test lamp for the left blinker was not working. So it appears the issue was not with the trailer after all. The test lamp for the brakes and right blinker work fine. I have replaced the 10 amp fuse in the C56106 thinking that might be the issue, but that did not resolve the problem. We checked to see if there was power reaching the outlet and there is. Could there be an issue with the converter in the C56106 itself? Is this an issue you’ve heard of before? I’m running out of things to check to find out where the problem lies. Thanks for any help you can provide!

asked by: Steve C

Expert Reply:

The problem you're having with Curt Wiring Harness # C56106 on your 2012 Toyota Sienna could be the converter box but first check the ground connection. Make sure it's grounded to a clean bare metal location on the van's frame. Since it worked before it's probably in a good spot but might just need to be cleaned which is an easy fix.

If the ground is good, you can test the converter box to be sure that's the issue. Use a circuit tester like # PTW2979 and test the yellow wire before and after the converter. If you have power before the box but not after, then the box is bad and needs to be replaced.

If the converter is bad, you likely have a short somewhere else that caused the box to go bad. Clean the trailer connector and inspect its wiring for any damaged or exposed wires before testing with a new harness so you don't continue going through them.

expert reply by: Patrick R