Speed-Dependent Volume

Speed-Dependent Volume

Diagram:

General
Automatic volume control is controlled by the car's speed to compensate for background noise that occurs when the car is moving.
The function is active at speeds over 60 kph.

Function
The ESP control module transmits a speed signal on the P-bus. This is read by the MIU. The MIU then transmits the information on the I-bus, which the head unit can read to regulate volume.
The level is increased when speed increases and is lowered when speed decreases.