The Car is a '95 E300 Diesel with the original Mercedes Becker Radio.

This Radio is supposed to raise and lower the speaker volume based on the current speed of my car. This feature however never worked.

While driving, I activated the Radio self mode test, and noticed that the Radio does recognize the speed of the car, as the it displayed different values for different speeds, yet the volume level did not change.

Any Ideas?

Thanks

Phil