Due to the increasing number of electronic control devices in modern automobile, the number of connecting wires is inevitably increasing. 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 the 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 signal transfer in the harness is also the wire connector. It can be said that in the electric control vehicle, the control computer ECU is the control center, the 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 convenience of 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 the electric control vehicle.           

Open circuit fault of conductor and connector may be caused by broken conductor in use, poor contact of connector and looseness of connector terminal. As the failure of wire disconnection in the middle is very rare, most of which is at the connector, therefore, it is necessary to carefully check the sensor and the wire in the connecting direction for looseness and poor contact. The open circuit fault of the connector caused by poor contact is often caused by the corrosion of the connector end and the external dirt entering the terminal or connecting socket, which results in the decrease of contact pressure. At this time, as long as the connector is removed, and then re inserted, to change its connection status, so that it can return to normal contact. Short circuit fault of wire and connector the fault of wire and connector may also be caused by short circuit between harness and body (ground wire) or inside relevant switch. Before inspection, first check whether the wire connector on the body is fixed firmly, and then test according to the following steps.

(1) Check whether the wire is on or off. 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 is not greater than 1 ohm, the wire is OK for the next check. When measuring the wire resistance, it is better to shake the wire slightly in the vertical and horizontal directions to improve the accuracy of measurement.

At the same time, pay attention to that most wire connectors and multimeter bars should be inserted from the back of the connector, but for the waterproof connector bar equipped with waterproof sleeve, it can not be inserted from the back, because a little carelessness in insertion will cause terminal deformation.

(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 value between each terminal of the connectors on both sides and the body. During measurement, one end of the meter bar shall be 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 means that there is no short circuit fault between the wire and the body.

For the appearance and contact pressure inspection of the connector, first remove each wire connector one by one, check whether there is rust contact and dirt on the connector terminal, and clean up the rust and dirt. Then check whether the terminal strip is loose or damaged, whether the terminal is fixed firmly, and whether the terminal is not loose when pulling gently. On the contrary, if the plug terminal in one socket is easier to pull out than other sockets, the socket may cause poor contact in use. Precautions during inspection

(1) the connector inspection must be carried out when the ignition lock is turned off, otherwise the relevant parts will be burnt due to self induction.

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