A new 2012 passageway 1.8T car with a mileage of about 27 thousand km. The car runs on the freeway. The customer calls the vehicle to press the horn and open the rain. The engine will burn out immediately. After the key is closed, the vehicle is restarted and the engine is running normally. But once again honking and wiping, the fault appears again. Fault diagnosis: after the vehicle enters the station the on-the-spot trial run, is consistent with the customer description. The engine runs normally without honking the horn and opening the rain; the headlights and the steering faults do not appear; press the horn, open the rain, and open the air conditioner, the engine jitter and immediately flameout. According to the fault phenomenon, it is analyzed that the fault should be connected to the line indirectly or improper, resulting in excessive resistance or "grab electricity" of the control circuit of the engine. First, when the inspection of the vehicle is not installed, it is found that the vehicle is installed with the global positioning system, and the line of the vehicle fuel supply control system is modified. At this time, the maintenance personnel suspect that the oil pump control circuit may be caused by the reloading of the line. There is a voltage drop in the trumpet and raining scraping, which causes the abnormal work of the oil pump and causes the engine to extinguish. So the oil pump control circuit of the vehicle is carefully checked, the line connection of the car fully meets the requirements, the power supply voltage of the oil pump is 12V when it is trumpet and raining, and there is no abnormal change. It shows that the oil pump control circuit is normal. Secondly, check the ignition switch and loudspeaker, wiper and air conditioner power circuit, the results are normal. The maintenance is in trouble at this time. Later, a common analysis was made with the technical manager. According to the car's phenomenon and the maintenance results, a common point should exist, that is, the horn, wiper, air conditioner should be used with the ignition system or the system to share a punch or power. So it looked up and analyzed the circuit of the car and found the problem. According to technical data, the three speakers, the wiper and the ignition coil eventually share a tie point of 640. Therefore, the check point was checked and found that the point was loose, and the trouble of debugging was eliminated after re fastening. Maintenance summary: the engine will immediately shake and flameout when the fault is trumpet and raining, the cause of the failure should be the control circuit that affects the ignition or fuel injection, not the control of the oil pump, because the vehicle should slow out when the oil pump is in problem and not immediately extinguish. Only if the ignition system or fuel injection circuit fails, will the engine stop immediately. Therefore, failure in the process of troubleshooting can not be eliminated in time, which is mainly the failure to accurately analyze the fault phenomenon, failure to correctly analyze the principle of line control, and not find the common point of the fault.