Troubleshooting Trailer Wiring of 2013 Subaru Forester, Fuse Blows with Headlights and Brake Pedal

Question:

This is an unusual one..I installed a C56040 from you guys to the factory trailer plug in rear of my 2013 Forester. All was fine while using it as a 4 way flat, but after adding brakes to my trailer I had to convert the plug to a 7 way and adding a separately run brake line direct from the battery with an in line 25 amp fuse. Now, it blows the 10 amp inline fuse from the C56040 about 2 seconds after pushing on brake pedal with the trailer lights on. The brakes work fine without the trailer lights on, and the fuse doesnt blow. The trailer lights work fine without the brake hooked up I used a 7way to 4 way adapter to try this. I cant see anywhere in the cars 7 way female plug or in the trailer junction box where the brake wire is touching any running/braking light wires. Ever heard of this one?

asked by: Clint H

Expert Reply:

The inline fuse of the Curt T-Connector Vehicle Wiring Harness # C56040 is for the amperage draw of the converter box. When you have the headlights on and press the brake pedal you essentially are asking the box to draw the maximum amount of amperage it will ever draw since basically you'll be lighting up every light on the trailer. So what's most likely happening is that your trailer is drawing too much power for the wiring harness.

This isn't uncommon and is most likely true if your trailer has incandescent bulbs. You can alleviate the draw on the trailer wiring by converting the lights to LED. I attached a page that has all of the LED trailer lights we offer as well.

expert reply by: Jameson C