Abstract: With the wide application of electronic technology in automobiles, automobile circuit diagram has become the necessary technical data for automobile maintenance personnel. At present, most cars are equipped with many electronic control devices, which are high in technology and complicated in circuit, so it is difficult to master them. It also needs some skills to read the automobile circuit diagram correctly. Circuit diagram is an important information to understand the work of various electrical systems of automobiles. It is very important to understand the types and characteristics of automobile circuits, the circuit characteristics and expressions of automobile systems, and the reading methods, rules and skills of circuit diagrams of various systems, so as to guide readers how to read and use circuit diagrams correctly.

The automobile circuit is a single-wire parallel circuit. Generally speaking, there are series, parallel and series-parallel circuits in local circuits. In fact, the whole vehicle circuit is composed of various circuits, and each circuit can be separated independently, simplifying the complexity. According to its basic purposes, the vehicle circuit can be divided into lighting, signal, instrument, starting, ignition, charging, auxiliary and other circuits. Each circuit has its own load conductor connected to the control switch or fuse box.