Troubleshooting Converter Box of Trailer Wiring Harness on 2014 Jeep Patriot

Updated 07/08/2014 | Published 07/05/2014

Question:

I have a question, I am having problems with my converter box. when I test the four pin plug all pins have 12.5 volts. this is with the jeep running or when it is off. No light will work.turn,stop,tail even though my jeep is brand new I still test the piggy plug on my factory harness when the tail or turn signal is on It gets power when it is the volts are zero. I believe the converter box is bad. PLease help

asked by: John M

Expert Reply:

You shouldn't be seeing voltage output unless one of the taillight functions is activated. The fact that you're seeing output, is a dead giveaway that the 12-volt battery feed circuit has internally shorted to the output circuits.

This is usually caused by a short circuit in the trailer wiring. The converter is designed to isolate the vehicle wiring from any shorts, so the relatively inexpensive converter gets damaged rather than the more expensive to repair vehicle wiring.

You would need to replace the trailer wiring harness. I'd recommend the Tow Ready # 118552. However, before replacing the harness, I'd recommend you locate the short circuit in the trailer wiring or else you'll continue to blow up converter boxes. Start at the connector on the trailer, and work your way back to each lamp. Make sure the connector isn't corroded or damaged. Check for pinched wires, loose connections or wire that has worn or cracked insulation that would allow the copper wire inside to touch the trailer frame and short out. Once the short is located and repaired, you can then replace the wiring harness.

expert reply by: Mike L