A new vacuum modulator on a Mercedes-Benz automatic transmission

The white thing is the vacuum modulator (not connected yet), two connection to measure the pressure inside the tranny. The black cable in the middle is an electric cable.

The modulator controls the modulation pressure: idle = high vacuum = low modulation pressure; full throttle = low vacuum = high modulation pressure. The modulation pressure controls the other pressures (working pressure, controlling pressure and regulating pressure).