Knowledge and Fault Analysis of Automotive Wire Connectors

Due to the increasing number of electronic control components in modern cars, the number of connecting wires is inevitably increasing. To ensure the correctness and reliability of wire connections, wire connectors play a very important role. A wire connector is a socket connected to a wiring harness, and all sensor wiring terminals use dedicated interfaces. The connection between the control computer ECU and all external components is through the connectors on the ECU, and the signal transfer in the wiring harness also uses wire connectors. It can be considered that in electric vehicles, the control computer ECU is the control center, the wiring harness is the neural network of the control system, and the wire connector is the relay station of the circuit wiring harness. However, in addition to being easy to install and accurately wired, connectors often experience malfunctions during use, with the most common being poor contact that leads to interruptions in network signal transmission, directly affecting the normal performance of electronic control vehicles. Wire and connector open circuit faults may be caused by wire breakage during use, poor connector contact, or loose connector terminals. Due to the rarity of wire breakage in the middle, most cases occur at the connector. Therefore, during inspection, it is important to carefully examine the wires at the sensor and connection points for looseness and poor contact. The connector open circuit fault caused by poor contact is often due to the corrosion of the connector end, and external dirt entering the terminal or connection socket, resulting in a decrease in contact pressure. At this point, simply remove the connector and reinstall it to change its connection status and restore normal contact. Malfunctions of wires and connectors may also be caused by short circuits between the wiring harness and the vehicle body (ground wire) or within the relevant switches. Before inspection, it is necessary to first check whether the wire connectors on the vehicle body are securely fixed, and then proceed with the following steps for testing. (1) Check the continuity of the wires Firstly, remove the wiring connectors on both sides of the control computer ECU and sensor, and then measure the resistance between the corresponding terminals of the connectors. If the resistance value is not greater than 1 ohm, it indicates that the wire is normal for the next step of inspection. When measuring wire resistance, it is best to gently shake the wire in both vertical and horizontal directions to improve measurement accuracy. At the same time, it should be noted that for most wire connectors and multimeter bars, they should be inserted from the back end of the connector. However, for waterproof connectors with waterproof sleeves, the bar should not be inserted from the back end because a slight mistake during insertion can cause terminal deformation. (2) Check the resistance value of the short circuit Firstly, remove the wiring connectors on both sides of the control computer ECU and sensor, and then measure the resistance value between each terminal of the connectors on both sides and the vehicle body. When measuring, one end of the meter rod should be grounded to the vehicle body, and the other end should be measured separately on the wire connectors on both sides. If the resistance value is greater than 1 ohm, it indicates that there is no short circuit fault between the wire and the vehicle body. (3) Appearance and contact pressure inspection of connectors Firstly, each wire connector should be dismantled one by one, and the connector terminals should be checked for rust and dirt. Rust and dirt should be cleaned. Then check if the terminal strip is loose or damaged, if the terminal is securely fixed, and if there is no looseness when gently pulled. On the contrary, if the plug terminal in a certain socket is easier to pull out than in other sockets, then that socket may cause poor contact during use. Precautions during Inspection (1) The inspection of the connector must be carried out with the ignition lock turned off, otherwise it may burn out the relevant components due to self perception. (2) When removing the wire connector, pay attention to loosening the locking spring or pressing the lock buckle, and do not forcefully pull or tug. When reinstalling, the connector should be inserted to the bottom and locked. (3) When disassembling and inspecting waterproof connectors, care should be taken to remove the leather cover carefully. The waterproof cover should be in place during installation, otherwise, water may enter the connector and cause circuit failure. (4) When checking the connector with a multimeter, do not apply too much force to the terminal when inserting the meter rod to prevent poor contact caused by deformation of the end piece.