A seventh generation TOYOTA Camry with a mileage of only 600km. Customer reflection: the vehicle has been automatically extinguished in recent days, and the engine can sometimes start the car immediately after the fire is extinguished, but sometimes it is necessary to start the engine many times. Vehicle failures are irregular, irregular, cold cars and hot cars. Recently, the phenomenon of automatic stalling is more frequent. Fault diagnosis: the technician starts the vehicle, the engine can run smoothly, the idle speed is steady, and the acceleration is strong. Using GTS to connect the vehicle DLC to diagnose the plug, while the vehicle information is read in GTS, the engine suddenly automatically extinguish. At this time, the engine fault light in the instrument is not lighted, and the engine fault light should be lit at this time. Turning the ignition switch "OFF" to "ON" position repeatedly, it is found that sometimes the engine fault lamp in the meter does not light when the ignition switch is in "ON" position. Judging from the fault phenomenon, the cause of vehicle failure is likely to be a problem in the power circuit of the engine ECM. In order to further confirm the cause of the failure, when the engine fault light in the instrument is observed, the engine is started, the engine is running but there is no sign of the car. When the engine fault lights on, the engine is started and the engine can start and run smoothly. The fault is caused by the ECM power circuit of the engine. The power circuit of the model ECM uses the engine ECM control. The opening and closing of the EFI main relay is controlled by the engine ECM, and the power of the sensor on the engine is also controlled, such as air flow sensor, air fuel ratio sensor, oxygen sensor and so on. The detailed control method is: when the ignition switch is in the "ON" position, the battery voltage is applied to the IGSW of the ECM terminal. At this time, the ECM terminal MREL output signal makes the current flow to the coil of the EFIMAIN relay, closes the contact and raises the power supply to the ECM terminal + B and + B2 and the engine sensor. When the ignition switch is repeatedly turned "OFF" to "ON" position, when the ignition switch is in the "ON" position and the engine fault light is not lit, use the multimeter to measure the related fuse of the ECM power supply circuit, and find that only the EFI2 and EFI3 fuse have no battery voltage. It shows that the EFIMAIN relay in the integrated relay of engine compartment 1 is not working. Take out the 1 integrated relay, but keep the connector plug open and check the wiring harness terminal with the test lamp. Found the connector 1C terminal 7 feet, 9 feet, 10 feet without battery voltage, normal is the test light should light, the connector 1C terminal 7 foot is the engine ECM terminal MREL input signal terminal two off the ignition switch to disconnect the ECM connector A26, measuring connector A26 terminal 44 and 1 integrated relay connector 1C terminal 7 wire harness between the resistance of infinitesimal It shows that the wire harness is guided to normal. Reconnect the ECM connector A26, put the test lamp into the 1 integrated relay connector 1C terminal 7, and rotate the ignition switch repeatedly "OFF" to "ON" position, and find that the test lamp can sometimes light and sometimes not light. At this point, it is proved that the engine ECM terminal MR-EL intermittently can not input the signal into the 1 integrated relay EFIMAIN relay coil, which causes the engine ECM not to work and the vehicle is extinguished.