What Causes a Fuse to Blow?
2 Answers
Reasons for a blown fuse are introduced as follows: 1. Washing the engine bay with water: When cleaning the engine bay, since the fuse box is not perfectly sealed, remember not to rinse the fuse box directly with water, as this can easily cause a short circuit in the fuse, leading to failure of the vehicle's electrical components. Most fuse boxes have a clear icon prohibiting water rinsing. If the fuse box is dirty, gently wipe it with a damp towel. 2. Installing high-power headlights: After modifying the headlights, excessive power can easily blow the fuse. It is advisable to promptly replace it with a higher-current fuse and power cable to prevent overheating due to excessive current. 3. Using high-power electrical devices like the cigarette lighter: The cigarette lighter fuse is extremely prone to blowing. Generally, cigarette lighters use fuses rated between 15-25A. Since the vehicle voltage is 12V, it is recommended that the electrical appliances connected to the cigarette lighter do not exceed 300W, and for some small cars, not exceed 200W. As for high-power devices like car refrigerators and air pumps, it is better to avoid using the cigarette lighter for power supply.
After driving for so many years, I've seen blown fuses mainly caused by excessive current. The most common reason is a short circuit in the wiring, such as when aging wire harnesses inside the car get damaged and touch the metal body, creating a strong current loop that burns out the fuse. Another cause is equipment overload, like plugging in high-power devices such as a car fridge or turning the audio volume too high, which exceeds the current limit and causes the fuse to blow immediately to protect the circuit. Last time, I drove long-distance with the AC on all night and blew a fuse. After stopping to check the fuse box, I found it was caused by a stuck wiper motor. Replacing a fuse yourself isn't hard, but you need to identify the root cause to avoid repeated failures. I recommend keeping a fuse kit in the car and regularly checking for loose or corroded wiring. This can prevent small issues from turning into big accidents, like short circuits that might drain the battery or, worse, cause a fire.