IG1 fuse blows when backing up

[Htrailblazer]

I pulled our camper out of storage for the year and started checking everything out. I have never pulled it with my 4runner before. I got it all hooked up and checked all lights and everything was working. I drove from the storage place to my house with no issues. then I backed it down my driveway. when I stopped i noticed that my instument panel for the mpgs and temp was blank. I also noticed that my turn signals had stopped working. I got out my voltmeter and started checking fuses. the IG1 15A fuse under the dash had blown. I checked the electrical connections again, cleaned everything replaced the fuse and went for a test drive. everything was good until i backed up the driveway again and the same fuse blows. so I know its probably in the trailer wiring but, am at a loss on what exactly it would be. the trailer does have reverse lights and have worked with other vehicles fine, specifically a 2002 durango and a 1998 f150. any suggestions would be great.

 

[NeutronJon]

See schematic attached below.

Since you noticed that the fuse only blows in reverse, it's most likely in your backup light circuit. I would start by unplugging the trailer light connection and see if the same thing happens. The four basic possibilities here are the reverse/park/neutral switch, one of your truck's light sockets is shorted to ground, the trailer reverse light socket is shorted to ground, or chafed wiring somewhere in between.

If you need help locating junction connectors, let me know. I can look them up for you.

If you don't have a multimeter, you're going to want to get a cheap one to help track this down.