Due to the increasing number of electronic control devices in modern vehicles, the number of connecting wires inevitably increases. In order to ensure the correctness and reliability of wire connection, wire connector plays a very important role.

The wire connector is a socket connected with a wire harness. All sensing terminals use special interfaces. The connection between the control computer ECU and all external components is through the connector on the ECU, and the wire connector is also used for signal transfer in the wire harness. It can be considered that in the electronically controlled vehicle, the control computer ECU is the control center, the harness is the neural network of the control system, and the wire connector is the relay station of the circuit harness. However, in addition to the convenient installation and accurate wiring, the connector often fails in use, and the most common failure is poor contact, which leads to the interruption of "network" signal transmission, which directly affects the normal performance of electronically controlled vehicles. Wire and connector open circuit wire and connector open circuit fault may be caused by broken wire, poor connector contact and loose connector terminal.

As the fault of wire disconnection in the middle is very rare, most of which are disconnected at the connector, the inspection should focus on carefully checking whether the wire at the sensor and connection is loose and poor contact. The open circuit fault of the connector caused by poor contact is often due to the corrosion of the connector end and the external dirt entering the terminal or connecting socket, resulting in the reduction of contact pressure. At this time, just remove the connector and re insert it to change its connection condition and restore its normal contact.

Short circuit fault of wire and connector

The fault of wires and connectors may also be caused by the short circuit between the harness and the vehicle body (ground wire) or inside the relevant switch. Before inspection, first check whether the wire connector on the vehicle body is firmly fixed, and then test according to the following steps.

(1) Check the wire for continuity

First remove the wire connectors on both sides of the control computer ECU and the sensor, and then measure the resistance between the corresponding terminals of the connector. If the resistance value is not more than 1 ohm, it indicates that the wire is normal for the next inspection. When measuring the wire resistance, it is best to gently shake the wire in both vertical and horizontal directions to improve the accuracy of measurement. At the same time, it should be noted that for most wire connectors and multimeter rods, they should be inserted from the rear end of the connector, but for waterproof connectors with waterproof sleeves, the rods should not be inserted from the rear end, because the terminals will be deformed if they are inserted carelessly.

(2) Resistance value check of short circuit

First remove the wire connectors on both sides of the control computer ECU and the sensor, and then measure the resistance between the terminals of the connectors on both sides and the body. During measurement, one end of the meter bar is grounded to the body, and the other end shall be measured on the wire connectors on both sides respectively. If the resistance value is greater than 1 ohm, it indicates that there is no short circuit between the wire and the body

Connector appearance and contact pressure inspection

First, remove each wire connector one by one, check whether there is rust contact and dirt on the connector terminal, and clean the rust and dirt. Then check whether the terminal strip is loose or damaged, whether the terminal is firmly fixed, and whether the terminal is loose when gently pulled. Conversely, if the plug terminal in which seat hole is easier to pull out than other seat holes, the seat hole may cause the fault of poor contact in use.

Precautions during inspection

(1) The inspection of the connector must be carried out with the ignition lock off, otherwise the relevant parts will be burned due to self induction.

(2) When removing the wire connector, pay attention to loosen the locking spring or press the latch, and do not pull hard. When reinstalling, insert the connector to the bottom and lock it.

(3) For the waterproof connector, when removing and testing, pay attention to carefully remove the leather cover, and the waterproof cover shall be in place during installation, otherwise the circuit fault may be caused by water entering the connector.

(4) When checking the connector with a multimeter, do not use too much force on the terminal when inserting the meter rod, so as to prevent poor plug-in contact due to the deformation of the end piece.

The competition among harness manufacturers has become white hot. When the product develops to a certain period, the competitors will also compete in enterprises with scale, strength and integrity. Smaller enterprises will be eliminated. Harness assembly is increasingly concentrated in enterprises with technical strength. Because the automobile harness is different from the general harness, some electronic components are the automobile harness attached to the automobile harness, such as the mixed installation of sensors and thick film circuits. The technical content of such electronic components is high, and the emphasis on technical safety has gone beyond simple and general assembly.

It is reported that a mid-range car has nearly 1000 connecting interface car harnesses, more than 30 microprocessors and hundreds of docking plug-ins. The total length of wires used is 1500m-2000m. With the development of IT technology, the concept car has put forward the development direction of automobile networking and modularization. The network cluster is ready to emerge, which will make the manufacturing technology of harness a second leap. The function of wire harness is expanded from ordinary signal transmission to data transmission.

In addition, due to the limitation of wire transmission signal, a large number of optical cables will be used, so that the manufacturing technology of automobile harness will usher in the third leap. Optical cables have the advantages of fast transmission speed, large capacity, small volume, strong confidentiality and good anti-interference. They will soon become an important preferred material for automobile data processing and exchange in the future, and make the power and signal distribution system enter a new historical stage of development. At present, on BMW's D-class car, Optical cable technology has been used, and Japan has followed suit and entered the actual loading stage.