Car wires, also known as low-voltage wires, are different from ordinary household wires. Ordinary household wire is copper single core wire, there is a certain hardness. The car wires are copper multi-core flexible wires, some soft wires are as thin as hair, several or even dozens of soft copper wires are wrapped in plastic insulated tubes (polyvinyl chloride), soft and not easy to break. Due to the particularity of the automotive industry, the manufacturing process of automotive wiring harnesses is also more special than that of other ordinary wiring harnesses. There are roughly two types of systems for manufacturing automotive wiring harnesses: 1. Divided by European and American countries, including China: TS16949 system is used to control the manufacturing process. 2. Japan-oriented: Toyota, Honda, they have their own system to control the manufacturing process. With the increase of car functions, the general application of electronic control technology, more and more electrical parts, more and more wires, and the wire harness will become thicker and heavier. Therefore, the advanced automobile has introduced the CAN bus configuration and adopts the multiplex transmission system. Compared with the traditional wiring harness, the multiplexing device greatly reduces the number of wires and connectors, making the wiring easier.

The common specifications of the wires in the car wiring harness are the nominal cross-sectional area of 0.5, 0.75, 1.0, 1.5, 2.0, 2.5, 4.0, 6.0 and other square millimeter wires (the nominal cross-sectional area commonly used in Japanese cars is 0.5, 0.85, 1.25, 2.0, 2.5, 4.0, 6.0 and other square millimeters). They each have an allowable load current value, with wires for different power electrical equipment. Taking vehicle wiring harness as an example, 0.5 specification line is suitable for instrument lights, indicator lights, door lights, ceiling lights, etc. 0.75 specification line is suitable for license plate lights, front and rear small lights, brake lights, etc. 1.0 specification line is suitable for turn signals, fog lights, etc. 1.5 Specification line is suitable for headlights, horns, etc. Main power lines such as generator armature wire, lap wire, etc. require 2.5 to 4 square mm wire. This only refers to the general car, the key depends on the maximum current value of the load, such as the battery wire, the positive power cord is a special car wire used alone, their wire diameter is relatively large, at least more than ten square millimeters, these "big" wires will not be woven into the main line bundle.
Before arranging the wiring harness, draw the wiring harness diagram in advance, which is different from the circuit schematic diagram. The circuit schematic is an image that describes the relationship between the various electrical parts, which does not reflect how the electrical parts are connected to each other, and is not affected by the size and shape of the individual electrical components and the distance between them. The wiring diagram must take into account the size and shape of the individual electrical components and the distance between them, and also reflect how the electrical components are connected to each other. After the technician of the wiring harness factory makes the wiring harness wiring board according to the wiring harness diagram, the worker will cut the wire and arrange the wire according to the regulations of the wiring board. The main line bundle of the vehicle is generally divided into the engine (ignition, electric injection, power generation, starting), instrumentation, lighting, air conditioning, auxiliary appliances and other parts, with the main line bundle and branch wiring harness. A vehicle main line has multiple branch harnesses, just like tree poles and branches. The main line bundle of the vehicle often takes the instrument panel as the core part and extends back and forth. Due to the length relationship or convenient assembly, the wiring harness of some cars is divided into the front wiring harness (including the instrument, engine, front light assembly, air conditioning, battery), the rear wiring harness (taillight assembly, license plate light, luggage light), the top wiring harness (door, top light, speaker) and so on. Each end of the wire harness will be marked with numbers and letters to indicate the connection object of the wire, and the operator can see that the mark can be correctly connected to the corresponding wire and electrical device, which is particularly useful in repairing or replacing the wire harness. At the same time, the color of the wire is divided into monochrome line and two-color line, and the use of the color is also specified, which is generally the standard customized by the car factory. China's industry standard only specifies the main color, such as the provision of single black dedicated to the wire, red monochrome for the power cord, can not be confused. The cord is wrapped with woven thread or plastic adhesive tape, for safety, processing and maintenance convenience, woven wire wrap has been eliminated, and is now wrapped with sticky plastic tape. The connection between the wiring harness and the wiring harness, and between the wiring harness and the electrical parts, adopts the connector or the wire lug. The connector is made of plastic and has a plug and socket. The wiring harness is connected with the wiring harness, and the connection between the wiring harness and the electrical parts is connected with the wiring harness or the wire lug.
Automotive wiring harness material requirements are also very strict: Including its electrical performance, material dispersion, temperature resistance, etc., are higher than the general harness requirements, especially when it comes to safety: such as the direction control system, the harness of these important components of the brake, the requirements are more stringent.