Why Does My Trailer Fuse Keep Blowing On My 2019 Toyota Tundra?

Updated 08/01/2022 | Published 07/30/2022

Question:

Using the 7 way tester on 2019 Tundra, the 12V light would not light up all other lights lit up successfully. Identified that the 40 amp SUB BATT fuse was blown. Once this fuse was replaced, the 12V lit up. Any idea as to what would cause this particular fuse to blow or where to even start looking?

asked by: Dan

Helpful Expert Reply:

One of the most common reasons that your fuse may have blown is likely due a short circuit that is overloading your circuit.

More commonly this is caused by a dirty or corroded trailer connector on your vehicle. I recommend start by checking for corrosion and rust, and if there is clean the connector and check to see if the issue persists.

If your connector is fine, then I recommend checking your trailer wiring as your SUB BATT fuse is your trailer towing fuse. You'll want to check for pinches or frays, and replace as needed if need be.

Additionally, you can use a circuit tester # PTW2993 to narrow down troubleshooting when checking for problematic wires.

I have also included a FAQ for you to check out as well.

expert reply by: Bryce D