The Chevrolet sail SLX car with a mileage of about 106 thousand km. All doors, including luggage, can not be operated by the central control door lock. Fault diagnosis: test the lock and lock signal input on the 2 front doors with a test lamp, and the correct input signal is detected on the corresponding terminal of the central control door lock module. Then check the 2 power input and earthing circuits of the central control lock module with the test lights, and the power and grounding conditions are good. Carefully remove the central control door lock module and suddenly smell a burnt smell. After careful observation, it was found that the contact terminals of the central control door lock module were blackened due to overheating. Such a large current can only be generated by short-circuit fault on the power supply line. With a question, the electric circuit related to the energy supply line is detected by a multimeter, and it is found that the resistance value of the 2 wiring of the motor motor connected to the actuator is equal to zero. That is to say, the insulation coil of the motor is broken and connected to the body with the actuator housing. After removing the trunk actuators, there was also a bit of burnt smell. After replacing the electric actuator and the central control door lock module, the trouble is completely eliminated. Fault analysis: due to the quality problem of the electric motor motor of the rear luggage case, the motor coil line and the outer shell are cast iron, which makes the large current transiently pass through the power supply line of the central control door lock module, and supplies the output of the module to the dual relay and the contact arm burned, resulting in the failure of the central control door lock module.