Troubleshooting Trailer Wiring Stop Turns Signals of 2007 Hyundai Santa Fe

Question:

Hello, I recently purchased a 2007 Hyundai Santa Fe that has a trailer wiring harness connected up off the rear lights. It powers the running lights on my utility trailer but not the brake or turn signal lights. I checked the trailer on my other car and it works fine, so its definitely not the trailer. I fitted a tester to the 4 pin and the right turn signal works fine, but the brakes work intermittently and the left turn signal only flickers. So, Im guessing its either an issue with the grounding of the harness to the car, or the converter box is at fault. I will check for the former and test for the latter. Before I do so, with the symptoms above can you suggest any other possible issues? All lights on the car work fine and there is no separate fuses for the towing harness.

asked by: Iwan D

Expert Reply:

I think you are on the right track and that it's very likely it's the wiring connections for the trailer wiring or the converter box, but even easier than that it might be just corrosion on the pins of the connectors. Try cleaning the pins with sandpaper to see if that improves the contact and allows the pins to work properly.

To test the converter box what you will want to do is test the wires going into the box of the converter box for voltage with a circuit tester like the # PTW2993 to see if there is voltage going into the box when the taillight functions of your vehicle are applied, and then test the output side of the box to see if the current is making it through the converter. If not then the problem is that the converter box has shorted itself out and would need to be replaced.

Before you replace it you will want to inspect the wiring of your trailer to see if you can find anything that would cause the box to short out like corrosion or cut/exposed wiring. These boxes don't usually go out unless there is a short on the trailer that takes it out.

If there isn't input voltage for the converter then the problem is the wiring of the wiring kit. You will need to check to make sure it's making a solid connection to the correct circuits.

expert reply by: Jameson C