The mileage is about 129 thousand km, which is equipped with BGC1. 8T, wheel supercharger engine, matching 01 V5 automatic gearbox 2007 Volkswagen Passat control car. Customer response: the car switches on the small light switch, and Li Xianggai automatically opens. Inspection and analysis: first turn the switch to the small lamp position and find that the lid of the trunk is automatically opened, and the fault barrier is exactly consistent with the customer description. After communication with customers, it was found that the fault occurred after the accident occurred on the right side of the vehicle, but the lid of the luggage case was not deformed because of the accident, and the preliminary analysis of the fault may not be directly related to the previous accident. The customer also reflected that the fault had been checked once, and asked the repairman who had last repaired the vehicle to know that the lock button was replaced by the cover of the trunk (in the middle of the rear of the cover of the trunk), and there was no failure in the short time after the replacement. Because of the same failure, the customer went to the factory to repair it again. The light switch was rotated to the small light position. The cover of the trunk was opened automatically and could not be closed; the light was closed and the cover of the trunk could be closed. Remove the suitcase cover plate, pull the plug of the trunk lid motor, measure the voltage of the 2 pins of the plug for 0V; turn off the suitcase cover lock and find the voltage to 12V; the opening of the trunk cover is controlled by the comfort system control unit, indicating that the fault point may appear in the input circuit of the comfort system control unit. The power line of the trunk lid motor can be determined that the power line of the motor is not short circuited with the power supply of the light. Because the trunk lock is locked in the open state, the plug of the motor is not power. The plug of the motor has power in the state of the trunk lock closed. This indicates that the power supply of the light lamp is short circuited with the opening switch of the trunk cover. The system control unit mistakenly believes that the switch on the trunk lid has been connected. The circuit diagram shows that there is a plug connection between the switch E234 and the comfort system control unit, which is located in the middle left side of the trunk cover. When the light switch is connected, the voltage of the brown / blue pin of the plug is measured to be 12V, which further confirms the short circuit of the switch of the trunk lid switch and the small lamp. There are 2 switches on the trunk lid of the car, one switch is E234 and the other is E188. The switch E234 is installed in the middle of the rear lid of the trunk lid and has been replaced during the 1 maintenance. The switch E188 is installed at the bottom of the driver's door trim panel. The opening signal of the 2 switch is entered into the control unit through the T23/2 pin of the comfort system control unit, which may be caused by the short circuit of the switch E188 contact and the light. E188 also has a key lock stop switch E232, turning the switch E232 into an angle, cutting off the connection between the switch E188 and the comfort system, manipulating the switch E188, and the luggage cover will not work. Turn the switch E232 to turn on the small light and find that the lid of the trunk doesn't open, indicating that the fault is caused by switch E188. Troubleshooting: change the switch E188. Summary and analysis: in the failure case, the customer describes a main "clue" when the small switch is switched on and the trunk cover is automatically opened. Check according to the fault phenomenon and check the circuit diagram, and finally eliminate the trouble.