Due to the increasing number of electronic control devices in modern automobiles, the number of connecting wires is inevitably increasing. To ensure the correctness and reliability of the connection of wires, wire connectors play a very important role.
The wire connector is a socket with a wire harness. All sensing terminals use a dedicated interface. The connection between the control computer ECU and all external components is through the connector on the ECU, and the signal transfer in the harness is also used. Line connector. It can be considered that in an electronically controlled automobile, the control computer ECU is the control center, and the wiring harness is the neural network of the control system, then, 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 during use, and the most common failure is poor contact, which leads to the interruption of the "network" signal transmission, which directly affects the good performance of electric control vehicles Play normally.
Wire and connector open
The wire and connector open circuit failure may be caused by the broken wire during use, poor connector contact, and loose connector terminals.
Because the fault of disconnecting the wire in the middle is very rare, most of them are disconnected at the connector. Therefore, the inspection should focus on carefully checking the sensor and the wire along the connection, whether there are loose and poor contact.
Connector disconnection failure caused by poor contact is often due to the connector end being rusted, and the external dirt enters the terminal or connection socket, resulting in a reduction in contact pressure. At this time, as long as the connector is removed, then re-inserted to change its connection status, so that it can return to normal contact.
Wire and connector short circuit fault
The failure of wires and connectors may also be caused by a short circuit between the wiring harness and the body (ground) or inside the relevant switch. Before the inspection, you should first check whether the wire connector on the vehicle body is firmly fixed, and then you can test according to the following steps.
(1) Check the continuity of the wire
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 greater than 1 ohm, it means that the wire is normal for the next inspection. When measuring the resistance of the wire, it is best to gently shake the wire in the vertical and horizontal directions to improve the accuracy of the measurement. At the same time, note that most wire connectors and multimeter rods should be inserted from the rear end of the connector, but for the installation A water-proof connector with a water-proof cover cannot be inserted from the rear end, because the terminal may be deformed by careless insertion.
(2) Check the resistance value of the 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 the measurement, one end of the meter bar is grounded to the car body, and the other end is measured on the wire connectors on both sides. If the resistance value is greater than 1 ohm, it means that there is no short circuit fault between the wire and the car body.
Connector appearance and contact pressure inspection
First, each wire connector should be removed one by one, and the connector terminals should be inspected for rust and dirt, and the rust and dirt should be cleaned. Then check whether the terminal strip is loose or damaged, and whether the terminal is fixed firmly. When the terminal is pulled gently, there should be no looseness. On the contrary, if the plug terminal in which seat hole is pulled out is easier than the other seat holes, the seat hole may cause failure of poor contact during use.
Precautions during inspection
(1) The inspection of the connector must be carried out with the ignition lock turned off, otherwise the related parts will be burned due to self-induction.
(2) When removing the wire connector, pay attention to loosen the locking spring or press the lock, do not pull hard and pull hard. When reinstalling, the connector should be inserted to the end and locked.