How to Tell if Your Car Fuse Is Blown (& How to Fix It)

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Easy steps to find and check your fuses
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Every electrical function in your car connects to a circuit, and fuses prevent circuits from carrying too much power that can damage your vehicle’s wiring. In other words, if something in your vehicle requires electricity, it has a dedicated fuse. When a circuit is overloaded, the fuse burns out to protect the electrical component from being damaged. This will cause sudden electrical failure inside your car. Here, we’ll cover common signs of a blown fuse, plus how to find and fix them.

How to Tell if a Car Fuse is Bad

Remove the fuse and hold it up to the light to find the wire, which looks like an upside-down U. If that wire is cut, separated, or burnt, the fuse is bad. If the wire is symmetrical and connected though, the fuse is perfectly fine.

Section 1 of 5:

Identifying a Blown Fuse

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  1. With a cold car, remove the fuse in question by hand or with the fuse removal tool that came with your vehicle. Car fuses are translucent, so hold the fuse up to a bright light and look inside. If the upside-down U-shaped wire inside of the fuse is physically broken, the fuse is bad. If that wire is symmetrical and connected as a single piece, the fuse is fine. [1]
    • A fuse is a safety device that keeps electrical components safe from too much voltage or power.
    • If you replace a bad fuse and it blows again, it’s a sign the problem isn’t the fuse itself—it’s whatever underlying component the fuse is protecting that’s causing the problem.
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Section 2 of 5:

Symptoms of a Blown Fuse

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  1. Which electrical system fails depends on which fuse gets blown out. If you have a bad fuse, you may also note a slight burning smell or see a “CHECK FUSE” light on your vehicle’s dashboard. Common issues caused by a blown fuse include: [2]
    • Radio stops working
    • Power door locks aren’t responding
    • Heater fan or AC isn’t operating
    • Power windows stop working
    • Windshield wipers don’t move
    • Power outlets aren’t functioning
    • Headlights, taillights, and interior light systems don’t turn on
Section 3 of 5:

Locating the Blown Fuse

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  1. Refer to your manual to find the fuse box and fuse diagram. In most cases, the fuse box is located under the hood near the steering wheel (under a plastic cover). Remove the fuse panel’s cover to reveal different color-coded fuses with stamped amperage ratings. [3]
    • Some vehicles have two fuse boxes—the main box in the engine bay and a second fuse box for auxiliary components under the steering wheel near the OBD-2 port.
  2. In most vehicles, the fuse panel’s cover will have an intricate diagram of the fuse panel components which lists the location and function of each fuse panel. This diagram should be in your manual, too. If you know you’re having an issue with your radio, search for a fuse labeled “radio.” Pull it out and inspect it visually to see if the wire is broken.
    • If the wire inside of the fuse is split, burnt, or torn, the fuse is bad. If the wire is connected and appears fine, the fuse isn’t the problem.
    • For example, a blown 30A Fuse on a 2023 Ford F-150 indicates an issue with the fuel pump door. [4]
    • If your vehicle does not come equipped with a fuse diagram, go online and search for a diagram based on the year, make, and model of your car.
  3. Alternatively, use a test light or multimeter to locate a blown fuse. Use a test light kit by attaching the clamp end of the test light to your vehicle’s negative battery terminal. Then, use the tool to tap the fuse’s pins on either side of the amperage rating. [5] If the fuse is working, the pen will light on either side of the pins. If only one side light up, the fuse is blown. [6]
    • Use a multimeter tool to test multiple fuses. Set the multimeter to 20K ohms, which is a rating that refers to the restriction of power. [7] Then, take the device’s protective tips off and touch both sides of the fuse. A good fuse will come up as 0.00. If you see a different number, the fuse is broken or damaged. [8]
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Section 4 of 5:

Replacing a Blown Fuse

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  1. Use the same type of fuse and amperage rating when changing fuses in a car. This will prevent further short-circuits or additional damage to your car. Push it back into the correct slot using your finger or a fuse puller. [9]
    • This is as simple as it seems. You just insert the fuse in the dedicated slot and gently push until the fuse clicks into place.
  2. Once the fuse has been replaced and the panel is covered, turn your vehicle on to see if the broken fuse is fixed. If working correctly, you should see immediate power to your vehicle’s radio, door locks, or whatever else was affected. If replacing the fuse doesn’t work, contact your local mechanic for a professional diagnosis. [10]
    • If you’re a home mechanic and the problem isn’t solved by replacing the fuse, the problem is likely the underlying component.
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Section 5 of 5:

What causes a car fuse to blow?

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  1. If your fuse continuously blows, make sure you’re using the correct amperage rating. A higher or lower-amperage-rated fuse can create frequent short circuits and cause extensive electrical damage to your vehicle.
    • If you’re in a situation where you can’t quickly access the correct amperage, use a fuse from an unused component. [11]
    • For instance, if your vehicle’s radio and headlights share the same amperage, use the fuse from the radio as a temporary measure so you can see in the dark.
  2. Short circuits result from a poor connection between the two conductors that supply electricity to your vehicle, often caused by internal damage. If this is the case, a professional mechanic will need to inspect the wiring and connection points to remedy the issue. [12]
  3. As with any wires, their protectant shell may fray over time and use, exposing the wires to the vehicle’s metal frame and other surfaces. When this happens, it can cause short-circuiting and lead to an electrical fire. [13]
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      References

      1. ↑ https://youtu.be/PF5G4llnvQs?t=107
      2. ↑ https://leasecar.uk/blog/most-common-car-fuses-to-blow-getting-back-on-the-road/
      3. ↑ https://www.dmv.org/how-to-guides/fuse.php
      4. ↑ https://www.startmycar.com/us/ford/f-150/info/fusebox/2023
      5. ↑ https://www.youtube.com/watch?t=79&v=o_AWj2fcQS4&feature=youtu.be
      6. ↑ https://www.youtube.com/watch?v=o_AWj2fcQS4&t=103s
      7. ↑ https://www.geniusaudiousa.com/blogs/news/what-is-car-speaker-impedance-and-why-is-it-important
      8. ↑ https://www.youtube.com/watch?t=49&v=ecHB8mliCbI&feature=youtu.be
      9. ↑ https://www.dmv.org/how-to-guides/fuse.php
      1. ↑ https://www.dmv.org/how-to-guides/fuse.php
      2. ↑ https://www.dmv.org/how-to-guides/fuse.php
      3. ↑ https://burtbrothers.com/tips/why-your-car-keeps-blowing-fuses-and-how-to-fix-them/
      4. ↑ https://burtbrothers.com/tips/why-your-car-keeps-blowing-fuses-and-how-to-fix-them/

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