A 2012 mileage Chevrolet Jingcheng car with a mileage of only 6000km. Customer response: the central control door lock of the vehicle can not be used normally, and the verification phenomenon can only be locked without using the remote control and the main auxiliary driving door lock switch. After taking the car: check the control door lock circuit diagram, the control door lock circuit to measure, switch to BCM signal line X, connector 20 voltage (Jie Suo) is 1.3V, normal value is 0, press switch has 1.3V change. Using 3A connection line to cross 20 and ground (analog switch) without unlocking action, normal BCM receives unlocking signal to control all door unlocks. Measuring switch to BCM signal line X1 connector 37# (locking) has 1.3V voltage, the normal value is 0, and there is 1.3V when pressing the switch. Use 3A connection line to cross 37 and ground (analog switch), four door lock latch, normal BFC receives unlocking signal will be controlled, there is door locking. Use the test lamp to connect the X3 door lock lock stop output signal 5#, unlock signal 6 and grounding, press the lock switch test light to light (BFC has voltage output), press the unlocked switch test light not to light (BFC no voltage output). The input signal line voltage of the door lock switch is not consistent with the normal vehicle, and there is no short circuit for the switch to X1 (20#, 37#) line measurement and the open circuit connector has no abnormal connection. Replace BFC, but the fault is still unchanged, replace the new key and remote control receiver to lock, unlock normal action. Maintenance summary: when the remote control receiver receives the lock or unlock signal, the door lock motor action is controlled by BCM. If the remote control receiver provides the wrong signal to BCM, the central control door lock will not work properly.