I tow a small pop-up camper often through the summer. Never had any problems with my electrical. I have also towed several other trailers for various reasons, and never had any electrical issues. This last weekend though, I towed my friends rented pop-up so he could tow my pop-up with his mini van (the rental was too heavy to tow behind his van). I kept blowing the hazard fuse (blinkers) and the brake light fuse. What gives?

 

Well the two things I can think of is either the round blinker in the fuse box isn't heavy enough but you've had no problems before so I don't think this would be it but wouldn't hurt to replace or the rental has an electrical short which is most likely the case.

 

A short in the rental was what I was thinking.

 

i think the brake light circuit in the rental was shorted to ground.
thank goodness for fuses.

 

Glad I we didn't but one of those expensive POS.

Sounds like a short in the camper. Check all the wiring on the camper.