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The mileage is about 15 thousand km, with 2014 Dongfeng Yueda KIA K2 cars equipped with 1.4L engine and automatic transmission. User response: all warning lights on the meter are lighted occasionally when the vehicle is running. Fault diagnosis: the customer to the store to do maintenance to reflect the vehicle in a maintenance cycle in a number of times in the running of all the warning lights on the instrument, but because the customer's description of the failure is very general, and the service consultant in detail with the customer to understand the fault information, the customer is not very specific, When you record the fault, you can only fill out all the warning lights in the running instrument occasionally. After receiving the car, the maintenance technician first completes the maintenance project according to the specified process, and then focuses on the breakdown described by the customer. These checks mainly include the connection between the power supply of the instrument and the iron and instrument connector, and these have not been found. Because of the failure is in the running, so the maintenance technician and drive to carry on the road test, the result of the road test more than ten thousand meters also did not appear the customer description of the failure phenomenon. Under the helplessness, we can only give the car to the customer, and explain some cases of this intermittent fault with the customer, and instruct the customer to contact us in time when the next failure occurs. One day in the second week of the customer's picking up the car, the customer called to my store and said that the fault appeared again. And when the failure occurred, the vehicle was in normal driving. The customer recorded the phenomenon of the instrument with the video function of the mobile phone after the car pulled over. Later, the video to our store was sent to the electronic mailbox of our store. Through this video our maintenance technician saw the whole process of the failure. In the video, we saw the engine fault lights on the instrument, the ABS system fault light and the water temperature warning light, and the speed meter pointer of the engine fell down. To zero, and the customer also said that when the fault occurs, the pointer of the speedometer is also directly back to zero. Later asked the customer that there was no change in speed and transmission gear when the fault occurred. When the video is recorded by the customer, the ignition switch is closed and the engine is started again after the ignition switch is closed. The failure phenomenon is completely disappeared, and the failure phenomenon will not appear again. The customer said that the failure actually did not affect the normal driving, but it was the trouble from time to time. This is a typical electrical system accidental fault, and the failure occurs when there is no regular time period, and there are no precursors. The only two condition is that the fault occurs in the course of driving. After the failure, the ignition switch is closed and then reopened, so the barrier phenomenon will disappear. Of course, customers have also said that sometimes when the failure occurs, if you continue to drive, a variety of warning lights will flicker automatically after a few times, and the pointer of the speed meter and the tachometer will automatically recover after the zero return. According to the specific phenomena of the fault from the occurrence to the disappearance of the car, we infer that there may be two reasons for the failure, one reason is the electromagnetic interference and the other is the bad contact in the line. Usually there are two kinds of electromagnetic interference: one is the electromagnetic interference occurring outside the vehicle, the other is the electromagnetic interference occurring inside the vehicle. The location of the car is not fixed at the time of failure, and through communication with the customer to understand that every fault occurs, the location of the vehicle is not easy to produce a number of electromagnetic interference sources, so that the external electromagnetic interference can be eliminated. The internal electromagnetic interference mainly comes from the starting system, charging system and ignition system, which are easy to generate high current electrical system. Although the electromagnetic interference inside the vehicle is also very possible, in fact, the car's fault in the 15000km mileage, a total of less than 10 times, then we can first assume that this failure is not affected by internal electromagnetic interference. In this way, the most likely reason for the rest is the poor contact of the related lines, so the problem that we should first eliminate and solve is the problem of the line. We found the circuit diagram of the model and read the part of the instrument. By looking at the circuit, we learned that the engine fault lights in the instrument, the ABS system fault lamp, the water temperature warning lamp, the tachometer and the speed meter were all connected to the same control chip. The information displayed by these indicators and speedometer mainly comes from the C-CAN communication line. If it is assumed that the instrument itself has no problem, the cause of the fault is most likely to be the contact problem of the C-CAN communication line, which shows that the 15 terminal of the M01-B connector of the K2 model instrument is the high potential line of the C-CAN communication line, the 16 terminal is the low potential line of the C-CAN communication line, and the two C-CAN communication lines of the instrument. Terminal 16 and terminal 21 of the I/P-C connector directly connected to the indoor safety box are connected to the C-CAN communication network through a safety box. If there is a bad contact between the instrument and the instrument, the most likely one is the two connectors between the instrument and the indoor safety box. The maintenance technician finds the two connectors on the real car, and then sloshing the two connectors in the state of the engine running, and when the M01-B connector on the instrument is sloshing, there is no change in the instrument. When the maintenance technician swings the I/P-C connector on the indoor safety box, the indicator lights of the instrument suddenly flicker a few times, and the phenomenon will not appear again when they continue to shake. Although we have not failed to test the phenomenon of failure, but also can basically determine the I/P-C connector in the indoor safety box has a bad contact problem, after the interruption is broken, it is found that the gap between the individual pins in the connector is slightly large, the gap between the pins is readjusted, and all the disassembled parts will be restored. Because we were not very sure of the car's fault, we once again told the customer to watch more when we delivered the car, and we kept in touch with the customer for nearly two months, and the fault of the car did not appear again within the distance of nearly 3000km. The trouble is ruled out. Failure summary: later we have learned from other 4S stores of the same brand that some of the individual vehicles of the K2 model have had similar problems. The general solution is to replug the I/P-C connector, or to adjust the gap between the pins of the connector, but there is also a bad need to replace the dashboard wire harness to solve the problem. If the basic reason is investigated, the author thinks that the material elasticity of the socket is too poor, and the gap between the inserts inserted during the assembly of the vehicle is deformed and the deformation can not be recovered in time, which leads to the bad contact. In this way, a sudden or temporary break occurs between the lines during the running of vehicles, resulting in the failure of the vehicle.