Troubleshooting Trailer Wiring that Stopped Working to See if It's Converter Box

Question:

I installed this wire harness on my Mazda CX-5 and it has been working for the past three years for my boat. However, it stopped working on my boat trailer. I tested the wiring with a tester and it has no power. I also replaced the fuse at the battery multiple times and nothing still. None of my wiring around the car is damaged. I also checked the ground wire and it is fine. What else can I do to make it work? It is weird that it stopped working after 3 years.

asked by: Iriana A

Expert Reply:

It's not uncommon for a trailer wiring short or overdraw to permanently damage the converter box of a trailer wiring harness like the # 118563. To determine if the converter box is at fault you'd need to test for voltage going into the box with a circuit tester like part # PTW2993 and then test the output wires for voltage as well. If they voltage is going into the box but not on the output side then you know the converter box is at fault and needs replacing.

expert reply by: Jameson C