Lateral Acceleration Sensor
WARNING: This page does not describe the selected car, but rather 26 other vehicles, including the 1999 Mercedes-Benz SLK230, 1999 Mercedes-Benz ML430, 1999 Mercedes-Benz ML320, 1999 Mercedes-Benz E430, and 1999 Mercedes-Benz E320. However, it is still accessible from the selected car via links, so may be relevant.
Lateral forces move internal spring/mass element (magnets) out of REST position into a position in relation to the Hall Sensor element which alters voltage signal informing ESP control module.