Trailer Left Tail Light is Not Working After Installing Trailer Wiring Harness on 2013 Toyota Venza

Question:

Are their any differences with model #c56079 and #56079. I know there is no c on the one model number. I used this on a 2013 venza and cannot seam to get the left side lights to work.

asked by: Arthur

Expert Reply:

There is no difference. Harness # C56079 is the part number we give the harness to indicate it is a Curt product. The manufacturers number for the same part is 56079.

You can test the 4-Way end of the harness to determine if the problem is with the harness or the trailer. Use a circuit tester such as # PTW2993 to test the pin that is right next to the one exposed pin. If you have power there, then the issue is on the trailer likely a bad ground.

Ground problems normally show up when there is more draw on a system such as when you have the running lights on and then use another function like a turn signal or brake light.

Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces.

The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help.

If there is no power on that pin, then you will need to test the wires going into the converter from the vehicle. If the signals are correct going in but not coming out, then make sure the white ground wire is grounded by itself to a clean bare metal surface. If it still is not working, then there is likely a problem inside the converter box, and it will need to be replaced.