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

Question

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

1

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

1

Answer 1

If your trailer has 7 wires running all the way back to the brakes, then yes, you can tap into the existing wiring. Each of your new brakes will have two wires for the brake magnet. One wire is for 12 volt power to the brake magnets and the other…

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Answer 2

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Answer 3

The difference between the Class II and Class III hitches has to do with their Gross Trailer Weight (GTW), their Tongue Weight (TW), and their Hitch Receiver Size. Class II trailer hitch receivers have a 1-1/4 inch receiver and can be rated up to…

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Answer 4

It sounds like you are speaking of the wires for the brake magnets. If this is correct, you will need to connect one of the wires to the brake controller output wire on your trailer connector and the other wire will need to be grounded to a clean…

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Answer 5

According to Blue Ox, it'll take an experienced installer about 4 to 5 hours to complete the installation of their #BX1128 Base Plate Kit on a 2016 Jeep Grand Cherokee. The install isn't what I'd call super-difficult, but the installation…

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Answer 6

A 4-Way trailer connector has the basic lighting functions only; running lights, left turn signal and brake lights, right turn signal and brake lights, and ground. A 7-Way has these functions and a 12 volt circuit, a circuit for electric trailer…

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Answer 7

The #84 spindle is just a common way to identify the spindle dimensions typically used for 3,500 lb axles. So instead of listing out the parts, people can just say they have #84 spindles and it's easier to know what fits it. The CE Smith Trailer…

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Answer 8

That's a very good question, we tend to be extra cautious and say to use 10 gauge wire because that would be more than enough. When you get into longer trailers that will end up using a lot of wire the heavier gauge wire becomes more necessary.…

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Answer 9

Even though I cannot comment specifically on the grease you used because I am not familiar with it, I can tell you the best grease for trailer bearings is a a grease with a rating of GC-LB, which just means it is made to withstand very high…

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Answer 10

Hey Jonathon thank you so much for all of that additional information! To haul your bikes behind your class C Sprinter motorhome, while flat towing your Mini, I recommend the Hollywood Racks RV Rider Bike Rack item #HLY64FR and the Roadmaster Dual…

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Answer 11

Hi Paul, you’re definitely on the right track here, and I can help you narrow this down with confidence. With your tandem 3,500 lb Dexter axles and 33 inch spacing, both the Dexter EZ Flex part #K71-652-00 and the Lippert Road Armor part #LC53CK are…

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Answer 12

The Demco Hydraulic Trailer Brake Actuator part #DM72VR should be a direct replacement for the Atwood 61101 Brake Actuator that you have now. This newest updated it rated at 7K instead of 6K. This is a bolt on option that mounts on 3" centers.…

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

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