Troubleshooting 4-Pole Wiring Harness C56018 Turn Signals on 2004 Saturn Vue

Question:

Hello, I purchased a #C56018 CUSTOM WIRING HARNESS from you. It was simple to install, but the turn signals are not always working correctly. When a turn signal is initiated the lights on the trailer dont always come on. Sometimes I have to turn the headlights on and off a few times to get the turn signal lights on my trailer to flash even though the turn signal was on and working on my vehicle the whole time. Once they are on, they work fine. But, it seams like an issue with the C56018, and not the wiring harness on my trailer. Do you have any suggestions how I can fix this problem? Thanks for your help. Cheers!

asked by: Justin H

Expert Reply:

Thank you for your purchase last year of a hitch, wiring harness # C56018 and other towing components for your 2004 Saturn Vue. I am happy to help you troubleshoot your trailer lighting issue.

The first thing to check is the ground pin on each of the connectors at the tail lights. These are the plug contacts that lead to the white ground wires. Check both vehicle side and the harness side connectors looking for a discolored or bent electrical contact pin inside the plugs. The issue could be as simple as contacts that are not applying enough contact pressure or that have over time oxidized. On an older vehicle this is not at all uncommon.

There are aerosol electrical contact cleaner products on the market, such as Caig De-Oxit, that can be sprayed on connectors with oxidized contacts to clean off that interfering corrosion.

Once you have inspected (and maybe cleaned) and reinstalled those connectors you can test the 4-pole plug without the trailer if you have a circuit tester like # PTW2993. This lets you test the vehicle side of things without the trailer's wiring being involved. Testing one half of the setup at a time is generally preferred. Apply the tester to each circuit, on at a time, while a helper activates the lighting function on the Vue.

You could also have corrosion on either the vehicle or trailer plugs. Inspect and clean them as you did the taillight plugs.

If you still have issues then disconnect the trailer and test it by itself using the car's battery or a spare battery that is well-charged. Connect the battery negative terminal to the plug's ground pin (again the one for the white wire) to see if the light operate with this direct battery power input. If they work fine this way then this tends to meant that the issue is in the trailer or vehicle wiring upstream of the lights.

expert reply by: Adam R

Patrick F.

4/18/2020

Ive had my hitch and harness for 2 years now, Very happy with them. Just recently my turn signals to the trailer quit. I have power into the converter lights and signals.. but nothing coming out to signals,but have power to lights..do these convertors go bad? Or what could it be, thank you

Chris R.

4/20/2020

If you tested for power going into the converter, but there's nothing coming out of it, this definitely points to a bad converter. They do occasionally go bad and there's unfortunately not an available fix other than just replacing it. If you can tell me what tow vehicle you have I'd be happy to make a specific recommendation.