Dang beat me to it

Back up light sensor on side of tranny. I would bet a cold one on it. Better get it before it shorts and melts because you will lose all the gear oil.

NAPA doesn't have the pigtail and plug but it appears to short out in the actual switch (which is only like 22 bux and NAPA does have it). Or just disconnect the wire and let it hang and see if you blow a fuse.

If it shorts all the way then the connector will melt.

let me know if this helps

 

I will get back under the truck tomorrow when I get off work and see if that bad boy is the problem

 

Replace the 15A with a 25A.. haha only kidding... Keep us posted. And I'll say thank you to everyone in advance. Electrical circuits can be hard to diagnose, and there's been a ton of useful information in this post.

 

Had the same problem ... it was my trailer light wiring shorting out ... I removed all the trailer light wiring and all was fine.

 

Well fellas I'm here to collect the cold ones bet on the backup light switch . I traced the wiring before going in and replacing the switch. I wiggled the stuff around with the lights no to see if I could find anything grounding out. I hear the sound of velcro so i move down the line and wiggle the drivers side wiring for the tail light. It looked like the 4th of july it sparked so much! I took some liquid tape and slathered that on and relocated the wires so they don't rub on the frame anymore. I drove all weekend so far on one fuse!