Due to the increasing number of electronic control devices in modern automobiles, the number of connecting wires is inevitably increasing. In order to ensure the correctness and reliability of wire connections, wire connectors play a very important role.
The wire connector is a socket with a wire harness, and all the 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 wire harness is also used by the wire connector. It can be considered that in the electronically controlled car, the control computer ECU is the control center, the wiring harness is the neural network of the control system, then the wire connector is the relay station of the circuit wiring harness. However, in addition to easy installation and accurate wiring, the connector often fails in use, and the most common fault is the poor contact that leads to the interruption of the "network" signal transmission, which directly affects the normal performance of the electronically controlled vehicle.
The conductor and connector are disconnected
Wire and connector disconnect faults may be caused by broken wires in use, poor connector contact, and loose connector terminals.
Since the failure of 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 at the connection line, whether there is loose and poor contact.
Connector disconnection failure caused by poor contact is often due to corrosion of the connector end and external dirt entering the terminal or connecting socket, resulting in reduced contact pressure. At this point, just remove the connector and reinstall it to change its connection condition and restore it to normal contact.
The cable and connector are short-circuited
The failure of wires and connectors may also be caused by a short circuit between the harness and the body (ground wire) or within the switch concerned. Before checking, we should first look at whether the wire connector of the body is fixed firmly, and then we can test it according to the following steps.
(1) Check whether the wire is connected
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 ohms, it indicates that the wire is normal for the next check. When measuring wire resistance, it is best to gently shake the wire in both vertical and horizontal directions to improve the accuracy of the measurement, while noting that for most wire connectors, multimeter rod should be inserted from the back end of the connector, but for waterproof connector rod equipped with waterproof sleeve can not be inserted from the back end, because a little careless insertion will deform the terminal.
(2) Check the resistance value of the short circuit
First, remove the wire connectors on both sides of the control computer ECU and sensor, and then measure the resistance value between the terminals of the connectors on both sides and the body. When measuring, one end of the meter rod is connected to the body with iron, and the other end is measured on both sides of the wire connector. If the resistance value is greater than 1 ohms, it indicates that the wire and the body have no short circuit fault.
Connector appearance and contact pressure check
First, remove each wire connector one by one, check whether there is rust contact and dirt on the connector terminals, and clean up the rust and dirt. Then check whether the terminal piece is loose or damaged, whether the terminal is fixed firmly, and the terminal should not be loose when gently pulled. On the contrary, if the plug terminal in one seat hole is easier to pull out than the other seat holes, the seat hole may cause a failure of poor contact in use.
Precautions during inspection
(1) The inspection of the connector must be carried out in the state of ignition lock closure, otherwise it will burn out the relevant parts due to self-induction.
(2) When removing the wire connector, be careful to loosen the locking spring or press the locking buckle, not hard pull and pull, when installing, the connector should be inserted to the end and locked.
