In the recent maintenance process, Roewe 550 car wiper motor often encountered abnormal sound and damage phenomenon. Fault diagnosis: many Roewe 550 cars have abnormal sound when they work on rainy days. After examination, the abnormal sound came from the wiper motor and found that the wiper motor had been soaked by rain. Further inspection found that the drain of the drain is blocked by the dirt, and the rain can not be discharged when it rains, thus producing water, and the motor is soaked in water for a long time, causing the damage of the motor to produce abnormal sound. Troubleshooting: in the daily maintenance work, we should take the initiative to check the drain of the drain and clean it in time so as to prevent the accumulation of water due to the closure of the drain, and cause the damage of the motor of the wiper. For vehicles damaged by wiper motor, the drain should be cleaned up before replacement of new parts, so as to solve the problem.