Installed Curt Wiring Harness C56406 But Lights Are Not Working Correctly

Updated 10/15/2024 | Published 08/05/2024

Products Featured in This Question

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

(195)

$102.00

Hook Probe Circuit Tester

(70)

$13.94

Question:

I have installed the wiring as instructed. However, I seem to be having some issues and need advice. When I plug in the trailer, not all lights are on as they should be. For example, the running light on the left Ill be on, but not the right. However, the break light on the right will work fine when pressing the brakes. Same thing with the indicator... One side works, and not the other. As far as I can see, all connections are proper. Is there a damaged wire somewhere? The vehicle works perfectly fine otherwise. Trailer works fine when connected to a different vehicle. Please help.

asked by: Hanre W

Expert Reply:

Hello Hanre, thanks for reaching out. The first thing to do here is to double check your ground. A bad ground can cause all kinds of weird intermittent signals like you are describing. Double check to make sure your ground is attached to good clean metal free of any paint, rust or corrosion. More often than not, fixing the ground will allow things to work normally. If the ground is good, and you are sure everything is connected correctly, I have to assume that there is an issue with the converter. You can test this by using a wire tester such as part # PTW2993 to test the wires going into and out of the converter box. If the input signal is normal on all 4 wires, but the output is not, the converter is bad and will need to be replaced.

expert reply by: Jesse M

Hanre W.

8/7/2024

Thanks Jesse, I have already tried to fix the ground, and it was the same after. I will try and mount it somewhere else. Do you recommend anywhere specific? (2020 Jeep Cherokee Limited). I have a suspicion that there may be an issue with the converter. I am not sure what the warranty for those are, will look into it since I purchased it in April.

Jesse M.

8/7/2024

@HanreW Any metal on the vehicle frame will work for the ground. When we installed this wiring on a 2020 Jeep Cherokee we put the ground right near the mounting flange for the trailer hitch on the driver side. If the metal area is painted you may need to scrape the paint away so the metal is bare. If it truly is an issue with the converter, the Curt Wiring harnesses come with a 1-year warranty so you are still covered. We do request that you test to confirm. If you want to do a warranty just give customer service a call.

Hanre W.

8/7/2024

@JesseM Awesome, thank you very much. I will have a look at that and see. I didn't scrape the area, so it could be the issue. Will do that and get back to you.

Jesse M.

8/7/2024

@HanreW Great. Let me know if I can do anything else to help!

Hanre

10/15/2024

Hi Jesse, I am back. So, I have been able to confirm that the issue is not with the vehicle wiring... The issue seems to be with the trailer. The right-side running light is not working. Also, the left side brake light is not working, however the blinkers/indicators both works fine... Which is strange, since it is the same wire/light (if I understand it correctly). Is there something I can look at specifically?

Jesse M.

10/15/2024

@Hanre that is strange. Has this trailer always had this issue? Or did it arise just recently? If this has always been an issue, my guess is the trailer is just wired wrong, or the connector may not be pinned properly. If the issue just arose recently, I would be looking for any damaged, frayed, shorted or disconnected wires on the trailer. Or you may have a bulb out. Trace each wire from the lights to the connector and look for any damage. A lot of times it can be easier to just re-wire the entire trailer. That way you can be guaranteed that things will work.

Hanre

10/15/2024

@JesseM Thanks a lot. I am going to sound like a fool here... So, when I got it, I picked it up I didn't check everything because I was in a rush. I just looked out the window and saw some lights on and assumed it good. I then thought for months that it was an issue with the vehicle harness. I replaced that and still had the same issue. That being said, I took it to an auto electrician, and he said the issue is with the vehicle. So, either he was talking crap, or the trailer has a ghost, or I have no idea what I am doing. So, with that in mind, an issue with the pin wired wrong is makes more sense now. I will go through the wires individually and see if I can find anything.

Jesse M.

10/15/2024

@Hanre One thing you can do is try plugging your trailer into another truck. If the same issues happen, then we know the trailer is the problem. If all of the lights work fine, we can narrow it down to the truck side. If you are sure the converter is good, it really does sound like a trailer side issue. A dirty or corroded trailer connector is another thing to check. Corroded or rust pins can cause lighting issues. Let me know if I can do anything else to help.