You are using your motor vehicle’s lane keep assist system while driving. The system does not respond when you depart from the lane. What could be the cause of this?

The combination of factors you've selected—inadequate road illumination, heavy precipitation, and a lack of lane markings—accurately reflects the various conditions under which a lane keep assist system may fail to function properly.

Each of these factors plays a significant role in the effectiveness of lane keep assist technology.

1. Inadequate road illumination can hinder the system's ability to detect lane boundaries, especially at night or in poorly lit areas.

2. Heavy precipitation can obscure lane markings due to water on the road, making it difficult for the system to identify where to guide the vehicle.

3. A lack of lane markings or faded road signs means the system has no reference points, causing it to become ineffective in maintaining lane discipline.

Understanding these factors is vital because they emphasize the importance of being aware of road conditions while driving. Should the assistance system fail, the responsibility lies with the driver to maintain control of the vehicle, as stipulated in German traffic regulations.