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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.
Steps
Locating the Blown Fuse
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Keep your vehicle off and locate the fuse box. 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.
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Identify the problem using the fuse diagram. 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.
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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]
Replacing a Blown Fuse
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Replace the old fuse with an identical one. 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.
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Test the circuit by powering your vehicle. 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.
Expert Q&A
Video
Tips
References
- ↑ https://youtu.be/PF5G4llnvQs?t=107
- ↑ https://leasecar.uk/blog/most-common-car-fuses-to-blow-getting-back-on-the-road/
- ↑ https://www.dmv.org/how-to-guides/fuse.php
- ↑ https://www.startmycar.com/us/ford/f-150/info/fusebox/2023
- ↑ https://www.youtube.com/watch?t=79&v=o_AWj2fcQS4&feature=youtu.be
- ↑ https://www.youtube.com/watch?v=o_AWj2fcQS4&t=103s
- ↑ https://www.geniusaudiousa.com/blogs/news/what-is-car-speaker-impedance-and-why-is-it-important
- ↑ https://www.youtube.com/watch?t=49&v=ecHB8mliCbI&feature=youtu.be
- ↑ https://www.dmv.org/how-to-guides/fuse.php