A Volkswagen Passat 1.8TSI car with a mileage of about 20 thousand km, carrying a CEA engine and a 0AM dual clutch transmission. It is a CEA car. User response: after the car accident is repaired, the lighting failure lights on the dashboard are lit up, and no way can be used to extinguish them. Inspection and analysis: a preliminary inspection by the maintenance personnel found that the daytime running light of the vehicle was not lit after starting the engine, which is abnormal. The body control unit is detected, and there is a fault indication for the LED day light to the short circuit / open circuit of the grounding. This is mostly due to the incorrect setting of daytime lamp control unit. Through the guidance function of the fault diagnosis instrument, we can see the long code of the daytime row lamp control unit, and find fifteenth bits of data 70, error. Troubleshooting: after the above data is changed to 30, the fault lamp is extinguished, and the daytime running lights are restored to normal.