The mileage is about 153 thousand km, and the 2009 Volkswagen Langevin car is equipped with 1. 6L engine and manual transmission. Customer response: the front and rear left and right rear windows of the vehicle do not move up or down. Check analysis: connect the ignition switch to operate the driver's door on the driver's door, the left front lift switch E40, the right forward and down switch E81, the left rear elevator switch E53 and the right rear elevator switch E55, find that all the doors can not be lifted. Operate the elevator switch E107 on the right front door individually to control the lifter operation of the door. The fault does exist. Next, use the vehicle diagnostic device VAS5051 B to enter the gateway installation list to check the malfunction. It is found that the electronic central electrical system (BCM) is in trouble. Enter the electronic central electrical system to check the fault code and the meaning, found that there are 1 fault codes - 01331, meaning: the driver's side door control unit J386 without signal / communication (static). According to the meaning of fault code and the preliminary analysis of failure phenomenon, the cause of the failure may be J386 itself damage, J386 power supply and grounding circuit breakage or BCM connection J386 LIN bus circuit breakage. After looking at the circuit diagram, it is known that the power supply of J386 is from the positive pole of the battery. The fuse SA2 on the battery cover goes to the fuse SC35 on the left side of the dashboard fuse, SC35 to the plug T10a/1 on the left A column, the plug on the J386 T10f/2 pin. The grounding is T10f/4 pin, and the location is below the left A column. Remove the left front door trim panel and pull the plug of J386 and measure the voltage of the T10f/2 and T10f/4 pins. The measurement result is about the battery voltage, which indicates that the power supply and grounding are normal. The LIN bus is the T73b/ 17 of the T10f/3 pins connecting the BCM through the plug T10a/10, and the LIN bus of the right front door control unit J387 is also the T73b/17 pin of the BCM. If the LIN bus is short circuited, the window lifter switch E107 of the right front car door can not control the window lift of the door, and the elevator switch E107 on the right front door can control the elevator work of the door, which indicates that the LIN bus does not have a short road. If the LIN bus connected to J386 breaks open, this will happen. Pull the plug of the BCM and measure the LIN bus without opening. After the above inspection, it is believed that the J386 is in trouble. After the replacement of J386, operate the lifter switch, and all electric windows are resumed. Troubleshooting: replace driver door control unit J386. Summary and analysis: when the vehicle is similar to the fault, the power supply, grounding and LIN line are all normal. It is recommended to replace the door control unit.