A micromechanical system for detecting an acceleration includes a substrate, a rocker-like mass structure having a first lever arm and a diametrically opposed second lever arm, the lever arms being situated tiltably at a distance to the substrate and about an axis of rotation to the substrate, and first and second electrodes being provided on the substrate. The electronic control unit evaluates the voltage signal that is being supplied as an energy supply and switches to diagnostic mode when the voltage signal is the uniform voltage signal supplied by the diagnostic device. The volume flow at the inlet of the main pump is changeable.