Why does the fuse blow as soon as I start the car?
2 Answers
The most likely reason for the ignition switch fuse to blow repeatedly is a short circuit or grounding issue in the related wiring. Here are the relevant details: 1. Fuse: A fuse, also known as a current fuse, is defined by the IEC127 standard as a "fuse-link." Its primary function is to provide overload protection. When a fuse is correctly installed in a circuit, it will melt and cut off the current when the current rises abnormally to a certain level and temperature, thereby ensuring the safe operation of the circuit. 2. Function: When a circuit malfunctions or behaves abnormally, the current may continuously rise, potentially damaging critical components in the circuit, burning out the circuit, or even causing a fire. If a fuse is properly installed in the circuit, it will melt and cut off the current when the current rises abnormally to a certain level and temperature, thus protecting the circuit and ensuring its safe operation.
I've encountered the issue of burning fuses upon ignition several times. Initially, I thought it was due to poor-quality fuses, but later discovered it's often caused by short circuits in the wiring. It could be that the insulation on the starter motor's wiring harness is damaged, causing the positive and negative terminals to touch and create an overcurrent. Alternatively, the generator's voltage regulator might be faulty, causing the output voltage to exceed 14V. I remember one time when I tried to fix it myself—I turned off all the loads, replaced the fuse, and tried starting the engine, only for the fuse to blow again. This indicates the problem lies in the main circuit. It's best to use a multimeter to check the voltage and current, and avoid randomly replacing the fuse with one of a higher amperage, as that could be more dangerous. I recommend taking it directly to a professional shop to inspect the entire starting system to prevent damage to the battery as well.
