See also:

Seat belt reminder
This symbol lights up to indicate that the driver has not fastened his/ her seat belt. ...

Limitations
Strong sunlight, reflections, extreme light contrasts, the use of sunglasses, or if the driver is not looking straight ahead may make the visual warning signal in the windshield difficult to see ...

The radar sensor and its limitations
In addition to being used by ACC, the radar sensor is also used by Distance Alert (see page 165) and Collision Warning with Full Auto-brake and Pedestrian Detection (see page 173). This sensor is ...