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Fault phenomenon: a Chery East son car, the engine is unable to machine fault (starter work is normal). Inspection and analysis: test the car after the crash. When the engine was checked, there was no high pressure fire and no fuel injection signal when starting the engine. It was doubted that the crankshaft position sensor had trouble, but it was checked and the abnormal situation was not found. Connect the fault detector to read the fault code and show that the system is normal. So the device was tested with a fault detector. Component test can operate low-speed operation of cooling fan, EGR valve, activated carbon tank solenoid valve, fuel pump relay and cylinder injector working condition check. When the cooling fan is operated with a fault detector, the cooling fan can operate at a low speed. The operating sound of a "carbazole" solenoid valve can be heard by both the EGR valve and the activated carbon tank solenoid valve. Then, when the fuel pump relay is operated, the sound of the fuel pump can not be heard. The suspected fault is related to the fuel pump relay, but checking the fuel pump relay is normal. At the fuel pump relay seat, measure the voltage on the relay No. 30 at the relay seat, and then the 30 terminals correspond to the holes and 27 terminals for short connection, and the fuel pump operation sound can be heard, and the electric power lines on the ignition coil and the fuel injector are measured, indicating that the power supply department of both of them provides a car reading car by the fuel pump relay. The ignition coil and the amplifier are made into one. There is a 3 wire end connector and its connection. The 3 knots of the 3 line end connector are signal lines (from the electronic control unit), the iron wire, the power line (from the fuel pump relay), and the inspection has not been detected. Analysis of inspection results and failure phenomena indicates that there may be problems in the ECU of the engine. The driver of the car was asked to know that the engine electronic control unit on the car was changed, because the electric control unit of the original car could control the ignition of the ignition coil of the 3 cylinder, but the 1, 4 cylinder ignition coils did not work, so the ECU was replaced. During this period, the ignition coils (ignition modules and ignition coils) that control the 1 and 4 cylinders are also replaced. Finally, the engine electronic control unit of the original car is installed, and the fault detector is used to enter the component test. Besides the other components are all working, the fuel pump relay is also working. Starting the engine, the engine can be activated. But the engine 1 and 4 cylinders can not be made, the engine seriously jitter. This indicates that the fault is caused by the damage of the ECU. Elimination method: replace the engine electronic control unit.