Lexus CT200 car. User reflection: the car window glass can not be lifted. Inspection and analysis: first, confirm the fault after receiving the vehicle. Connect the ignition switch to operate the left front window switch on the main control switch, the window glass can be normal and down; the other 3 windows switch on the operation master control switch and the 3 window glass without any action, but the window switch on each door can control the normal lift of its own window glass. According to the analysis of the fault phenomenon, the causes of the above failures are as follows: the main switch is damaged, the related lines are malfunctioning, and the main body ECU is damaged. The windows of the 4 doors of the car all adopt a one key lifting system, and each door has an independent control module. It does not use the main control switch to control the other 3 window glass elevator directly, but uses LIN to control it. The connection fault detector enters the main body system and looks at the relevant data flow, "win-dow lock switch SW". When the lock key on the main control switch is pressed, it is displayed as "ON" and is released after being released as "OFF", indicating that the lock key of the master switch is normal. Then check the LIN line. Because the LIN line covers a wide range, it is decided to start from the LIN2 signal terminal of the main ECU. In normal circumstances, the terminal should have a voltage of 12V and then extend to 4 wire harness connectors, namely terminal 11 of the connector KH2, connector JH2 terminal 11, terminal 32 of connector HP1, and terminal 57 of connector HQ 1, and these 4 connectors are parallel connections when a branch or connector of a parallel line appears. In the case of the problem, the voltage of the whole LIN line will be affected, so the 4 connectors are found and the voltages on the corresponding terminals are pulled out respectively. In the disassembly process, the connector KH2 and connector HP1 have serious water intake, some terminals have been seriously corroded, and the other 2 connectors are normal. It seems that the fault is caused by this. Troubleshooting: connector KH2 and connector HP1 terminal for corrosion treatment.