I never did figure out this problem. I tried many times and finaly gave up. I sold my truck last summer before I needed a new inspection sticker so I just lived without the reverse lights. Good luck.

 

Also try removing the rear back up lamps & see if the fuse pops. If not then the problem is around the lamp socket, or with one or the other lamp.

If it still pops with the back up lamps removed, then it sems to me, the problem is between the switch on the transmission & the rear back up lamp sockets.

Just some additional trouble shooting thoughts to ponder.

 

My fuse 26 problem ended up being a damaged T-connector where the trailer wiring hooks into the rear wiring harness. It's up underneath the rear bumper area.