Troubleshooting Trailer Lights Not Working Towing With Mazda CX-5

Question:

I added a wire harness Curt #56310 to 2016 Mazda CX-5 grand touring. When I plug in the 4 pin tester all test lights work as they should. When I plug in my boat trailer, no trailer lights work. Mazda light do work. When I plug the boat into my truck, all trailer lights work as they should. Boat trailer has LED lights. Why - does the tester work on the CX-5 yet when I plug in the boat trailer no trailer lights work?

asked by: David S

Expert Reply:

There can be issues like this on some trailers using LED lights where they don't work at all. More than likely your LED lights aren't drawing enough power and this is the reason the tester works but not the lights on the actual trailer. This also varies between vehicles which would explain why it works on the truck and not your CX-5. In order to simulate more current draw, you can use load resistors like the # DI34ZR. You will need one per circuit so in this case 3 for the right turn/stop, left turn/stop, and taillights.

expert reply by: Robin H