The automotive wire harness is a necessary and key connection part between automobile circuits. Without the wiring harness, there would be no automobile circuits and the car would not be able to start.

Automotive wire is a kind of low-voltage wire, which is different from copper single-core wires with certain hardness. Automotive wires are made of copper multi-core soft wires, Several or even dozens of soft copper wires are wrapped in plastic insulating PVC, which are soft and not easy to be broken.

Automotive wiring harness commonly use coppor wire with nominal cross-sectional area of 0.5,0.75,1.0,1.5,2.0,2.5,4.0,6.0 (mm2), each one has a certian maximum load current for different power devices. 1.0 (mm2) wire is suitable for car lights, such as turn signals, fog lights, trunk lights, low beam,front and rear lights, brake lights, etc.; 1.5 specification wire is suitable for headlights(high beam), horns, etc.; mains power wires such as generator armature wires, grounding wires requires 2.5 to 4 (mm2) of wire.

Design a wiring diagram is nessary before making wire harness assemby, it is general instruction for assembly. So the wiring diagram should take into account the size of each electrical components and the distance between them, but also clearly show how the electrical parts are connected between each other.

The automotive main wiring harness is generally fractionated into engine (ignition, EFI, power generation, starting), instrument, lighting, air conditioning, auxiliary electrical appliances, main wire harnesses and branch wire harnesses. A main wiring harness has several branch wiring harnesses. All wiring harnesses of the car are centered on the instrument panel and extended around. Some car wiring harnesses are divided into front wiring harnesses (including instruments, engines, headlight assemblies, front bumper wiring harnesses (doors, dome lights, audio speakers), etc.). The ends of the wire harness will be marked with numbers and letters to indicate where the wire is connected. Operators can see the marks clearly and correctly connect to the corresponding wires and electrical equipment, which is especially useful when repairing or replacing wiring harnesses. At the same time, the colors of wires are divided into single-color wires and double-color wires. There are also regulations on the use of colors. Generally,the standard is made by manufacturers.