Symbol light on on 1991 Mercedes-Benz 560SEL

The Symbol to the right of the brake light is on. The one that looks like the sun.Do you know what that is?

Asked by for the 1991 Mercedes-Benz 560SEL
You have a light out mine was the center brake light.
That sounds to me like the front brake pads wear sensors telling you that the brake pads in front need replacing soon.