Automotive fuses are protective devices in a vehicle's electrical circuit, similar to home fuses. When the circuit current is abnormal and exceeds its rated current, the fuse will blow, thus protecting the circuit from damage. The official name for automotive fuses is "fuse", which is usually divided into fast-blow fuses and slow-blow fuses.

Common automotive fuses include high-current fuses and medium-low current fuses. Medium-low current fuses are mainly divided into blade fuses (including automatic fuse box mini fuses), plug-in fuses, screw-in fuses, tube fuse boxes, and flat fuses. The common medium-low current fuse is a medium-sized ATO or small fast-blow blade fuse, which is suitable for circuits that carry small currents and short-time pulse currents, such as headlight circuits and rear glass defrosting circuits.

The working principle of the fuse depends on its two important working parameters: rated current and rated voltage. When using a fuse, the corresponding fuse should be selected according to the circuit's current and voltage. Generally, automotive fuses use a blade-type design, with a plastic housing and a fuse structure wrapped in zinc or copper. The metal fuse is connected to the pins.

The specifications of automotive blade fuses are generally from 2A to 40A, and the ampere value will be marked at the top of the fuse. If the fuse is burned and the ampere value cannot be identified, it can be judged by color. The color standard for automotive blade fuses is: 2A gray, 3A purple, 4A pink, 5A orange, 7.5A brown, 10A red, 15A blue, 20A yellow, 25A transparent, 30A green, and 40A deep orange.

Since there are many components and electronic devices on the car, each device will be equipped with a fuse. Therefore, for easy maintenance, when designing each car, the designer will concentrate all the automotive fuses in one place, that is, the fuse box. Generally, a car has two fuse boxes, one located in the engine compartment, responsible for the vehicle's external electrical appliances, such as the engine control unit, horn, glass wiper, ABS, headlights, etc.; the other is located near the driver's left side, managing the car's internal electrical appliances, such as window lifters, airbags, electric seats, cigarette lighters, etc.

The above is an introduction to automotive fuses and their working principles. When selecting a fuse, the corresponding fuse should be selected according to the circuit's current and voltage to ensure the safety of the circuit. If the fuse is burned, its ampere value can be judged by color.