Due to the increase of the number of electronic control units in the car, the data transmission capacity of each electronic control unit is also doubled, which requires better information transmission function of Automotive wiring harness, and then the wiring of automobile wiring harness is more and more complex. Drawing the electrical schematic diagram and circuit diagram of the whole vehicle; distributing energy for each electrical subsystem and circuit according to the electrical principle circle; determining the wiring form of the wiring harness; drawing the two-dimensional wiring harness diagram and three-dimensional wiring harness layout, these wiring harness design steps must be carefully considered.

In addition, there are some wiring harness design principles should also be taken seriously, strive to make the wiring harness wiring comprehensive and meticulous, without any defects.

1. The wiring harness between two moving parts must be fixed on each component, and the connection length of the harness should be more than 25 mm larger than the maximum replacement distance of the two components.

2. All wiring harness placed near moving parts shall have a clearance requirement of at least 50 mm. Under the maximum assembly tolerance of the wiring harness, the clearance between the harness installed on the power train and the components not installed on the power train shall be at least 19mm. Under the maximum assembly tolerance of the harness, under other operating conditions, this clearance is to ensure the entire range of motion of the moving part / assembly.

3. The gap between adjacent components of the harness unrelated to the harness shall be at least 6 mm, unless the harness is fixed to this assembly or there is an obstacle between the harness and the nearby moving parts.

4. The vehicle wiring harness branches must have sufficient slack (more than 25 mm below the minimum length of the harness) so that they do not need to add load to the connected sensors or other sensors.

5. In order to prevent the grounding strip from damaging any harness on the trunk, the minimum clearance between the grounding lug on the harness trunk and the main wire of the harness should be kept at 25 mm.