Troubleshooting 12 Volt Trailer Wiring Circuit that Stopped Working When Connector Was Miswired

Question:

I connected my 7 way trailer plug to my vehicle plug 180 degrees out. My brake controller showed the letters SH which I believe meant a short. When I hooked up the plug correctly, every function worked, but the trailer batteries were reading 10.5 volts and didnt seem to be charging. When I hooked the trailer up to campground power the batteries were still reading 10.5 volts. What, if anything, could I have done to the system? Further checking of my vehicle side of the 7 way plug showed it was putting out 14 volts across the 12V output pin and the ground pin. I hope I didnt mess up the brake controller or braking system on the trailer. I have a 2006 Nissan Pathfinder with brake controller and 7 way plug installed. Any advice or help would be appreciated.

asked by: Mike B

Expert Reply:

Most likely you blew a fuse related to the 12 volt power circuit for your trailer wiring harness. Check the diagram of the fuse box under the hood of your vehicle and check the condition of the fuse and replace as needed.

expert reply by: Jameson C