What Causes a Fuse to Blow?
2 Answers
A blown fuse is caused by a short circuit in the circuit. Below are specific symptoms of a blown car fuse: 1. The battery has power, but the vehicle cannot start: When you find that the vehicle cannot start, do not continuously attempt to ignite it. Continuous ignition attempts can cause the battery to continuously discharge, leading to a complete loss of power. 2. The tachometer is normal, but the speedometer shows zero: While driving, if the tachometer shows normal readings but the speedometer displays zero, and the ABS warning light is on, it indicates that the fuse corresponding to the ABS has blown. 3. Pressing the windshield washer switch does not spray washer fluid: This may be due to a blocked nozzle or freezing in cold winter conditions. Do not continuously press the windshield washer switch, as prolonged pressing can cause the motor to overheat and blow the corresponding fuse.
That time when my own car's fuse blew, it was quite a hassle. I remember driving home one night with the music turned up really loud, and suddenly the navigation screen went black. I quickly pulled over to check and found that one of the fuses in the fuse box had blown. It turned out that the issue was due to my modified audio system, which exceeded the factory-designed power capacity, causing an overload in the circuit and burning the fuse. When a circuit is overloaded, the current becomes too high, and the fuse acts as a protector—it blows to prevent more serious dangers. Similar causes include short circuits, such as aging wires or water ingress, where the positive and negative terminals accidentally touch. Additionally, unstable alternator voltage can also cause a fuse to blow instantly if the output is too high. I learned my lesson and now regularly check for damaged cables and avoid installing high-power devices. If a fuse keeps blowing repeatedly, it's best to take the car to a professional shop for a circuit test rather than trying to fix it yourself—safety comes first.
