1. Considering the convenience of installation and the feasibility of assembly process

1) The connector of the harness should be placed in a position that can be reached by hand, or it can be reached after simply removing some body parts. For connectors that can only be inserted and pulled out with one hand, the connector at the other end shall be fixed on the vehicle body.

2) The convenience and efficiency of threading and plugging operation under actual conditions can be satisfied by taking into account the hole space of the harness and connector, the sealing of the hole, and the fixing of the connector; For electrical equipment or switch with high maintenance rate, such as instrument, audio, air conditioning panel, the reserved length of rear end harness is convenient for plugging.

3) The connectors of the same model and color should not be arranged in adjacent positions, and the plug-ins should be well distinguished to avoid incorrect insertion during assembly and damage to the harness and electrical appliances.

2. Consider fixing and protecting the harness

1) According to the direction of the harness and the specific shape of the vehicle body, the fixed points shall be reasonably set within the linear distance without the fulcrum, and the distance between the two fixed points shall not exceed 300mm generally; A fixed point can be set at the inflection point of the obtuse angle; The two fixed points shall be arranged at the right angle inflection point; Avoid sharp corners and inflections of the harness.

2) According to the direction and size of the harness, reasonably select the fixing clip and mark its position. In the installation direction of the fixed clip, there must be enough space to facilitate the installation and removal of the clip.

3) Add a fixed point at a suitable position not more than 120mm in front of the connector at the connector position connected with other wire harnesses and electrical devices to reduce the vibration of terminals in the connector. Add a fixed point at the branch of the main harness, and the distance between the fixed point and the fulcrum shall not exceed 100mm.

4) In order to maintain the clearance between the harness and the surrounding area, some places need to use rigid pipes or plywood to ensure that the harness does not deform. In order to ensure the directionality of the harness, the clip with positioning should be used at some positions.

5) When there are many connectors, the fixed position should be considered. If necessary, the wire harness groove and wire harness bracket shall be designed. The parts that rub with the body due to wire harness leakage shall be protected with corrugated pipes.

6) Do not contact the sharp edge of the body directly to increase protection and prevent the sharp edge of the body from damaging the external insulation layer of the harness. The plug-in connected by vibration or moving parts should be fixed to prevent vibration from being transmitted to the harness.

3. Avoid disturbing surrounding parts

1) The harness shall be arranged along the edges and grooves (the wiring groove designed on the body) to avoid direct pressure on the harness. The clearance with the pipeline shall be uniform, and the clearance with the surrounding parts shall be reasonable; For example, for seats, it is necessary to consider whether there is enough clearance through the harness and whether there is friction with other parts.

2) When installing on vibrating or moving parts, the relevant harness must have sufficient length according to the actual situation. The reserved length is determined according to the vibration amplitude of the parts and the maximum movement stroke of the moving parts. Ensure that the reserved length can prevent vibration transmission to the harness and prevent the harness from bearing tension.

3) The clearance with moving parts shall be determined according to requirements, such as the clearance of wiper motor connecting rod, belt, fan, gear, cam, etc. Generally, it is required to be greater than 25mm. When arranging the shift mechanism, consider whether there is interference with the harness.

4. Avoid high temperature areas and pipes

1) Avoid the wiring harness layout too close to the high temperature area. If it cannot be avoided, add heat shield to protect the wiring harness (at least 80 mm above). For the harness without heat shield, the distance shall be at least 160 mm, such as the exhaust system, EGR, supercharging system and related valves and other high-temperature components. However, the harness shall be at least 200 mm from the high-temperature area of the exhaust muffler and at least 30 mm from the exhaust manifold.

2) Do not use the same fixing points as the fuel line and brake line, and do not cross or contact with the fuel line and brake line.

3) The wiring harness layout should also consider other surrounding pipes, such as water pipes, vacuum pipes, etc., and do not interfere with the contact with these pipes.

5. Through hole considering harness layout

1) At the initial stage of design, the position and structural shape of the through hole should be considered, and the relative position relationship between the position and other parts should also be considered.

2) If the harness passes through the sheet metal hole from the cab to the outside, the external harness must be lower than the wire hole to prevent the liquid on the harness from entering the interior.

3) When the four-door harness is connected with the cockpit harness, the wire hole on the door should be lower than the wire hole on the body side wall.

4) The reliability of rubber parts on the harness must be guaranteed. The rubber sleeve of the wire harness through hole must be installed reliably, and the rubber sleeve cannot leave the installation position during normal use.

6. Consider preventing electromagnetic interference

1) Avoid electromagnetic interference sources of parts and components, and arrange some signal lines as far away as possible from interference sources, electric horns, electrical appliances such as motors.

2) The power line of the sensor signal should avoid the power line of the high-current element, and the interval should be greater than 300 mm. Electrical appliances shall be reasonably arranged to shorten the length of signal line.

3) The tower iron lines of some key systems and important systems shall be arranged in a separate position to avoid interference from other tower iron lines.

7. Aesthetics

1) The harness layout should be natural and not far-fetched. If the harness of the engine room can be placed under the beam, do not put it on it; It can be put inside, not outside.

2) The direction of harness shall be consistent with that of accessories. In the projection direction, the harness shall be arranged horizontally and vertically in a checkerboard manner, and the harness shall be arranged in a inclined direction as far as possible.

3) The wiring harness layout should be coordinated in color and uniform in size. It is recommended that all wiring harnesses in the engine room use dark connectors. If the wiring harness above the engine is too messy, it is recommended to develop the entire wiring harness protective cover.

8. Other principles

1) Try to avoid vertical arrangement of connectors to prevent dust and water. Plugs shall not be arranged in the rainwater collection area or outside the vehicle. When they must be arranged in the above areas, protective measures shall be taken. Use rubber plugs or rubber sleeves, add vaseline into the plug-in and other methods to avoid the oxidation of the terminal surface caused by water ingress in the plug-in.

2) Consider its safety. In case of car collision, the harness shall not be squeezed. The wire harness is broken and the internal short circuit will cause a fire instantly, causing secondary injury to the driver and passenger.

3) The wiring harness layout should also be combined with the electrical principle, and the wiring harness direction and outgoing direction should be reasonably designed according to the requirements of the electrical principle.

4) The wiring harness layout should also be combined with its secondary suppliers, such as connectors, fasteners, rubber parts and other manufacturers, to select the appropriate design scheme through communication between both parties.