Troubleshooting Tail Light Converter on 2003 Ford Escape

Question:

I installed the wiring harness as per your video which went very well. When complete, I plugged into a new trailer to test. There was no drivers side lights on the trailer. The car lights worked fine. I plugged the trailer into a truck I have and the lights on trailer worked fine. By the way, the passenger side lights work fine on car and trailer. Any ideas?

asked by: Jim G

Expert Reply:

As a first step, use a circuit tester like part # PTW2993 on the 4-pole trailer connector. Turn on the left turn signal and test the pin on the connector being fed by the yellow wire. The tester should show voltage, and the light should blink along with the turn signal. This pin should also light up when the brake pedal is pressed. If the pin does not light up, check the connection point where the harness taps into the factory tail light harness. Make sure the connectors are firmly inserted into place until the locking tabs click.

If the harness is fully snapped into place, use the circuit tester and test the yellow wire on the input side of the converter box (while left turn signal is activated). Then, test the yellow wire exiting the converter box. If you have power on the input side, but not the output side, the converter box is faulty and should be replaced.

Before replacing the converter, you will want to closely examine the wiring on your trailer, even if it is brand new. A short circuit in the trailer wiring could have caused the converter to short out. Look for pinched wires or wires with cracked or worn insulation that would allow the copper conductor to short out to the trailer frame.

I have linked you to a video showing how to troubleshoot your converter.

expert reply by: Mike L