The Sensotronic Brake Control unit is a unique unit. Mercedes-Benz were one of the first vehicle manufacturers to employ a brake-by-wire system on a car (W211, R230). Called sensotronic (SBC), the system no longer relies on the driver to produce hydraulic pressure.
The brake pedal is connected to the computer (ECU) by wire (brake-by-wire). The sensors on the brake pedal will inform the computer how the pedal is pressed, for example how far, how fast etc. The computer will then dissipate the required force to each wheel via modulators.
The SBC module counts breaking cycles, after exceeding the value of 300000, an error message occurs.
It is a kind of protection for the mechanical parts like the motor, inside the traction system hydraulic unit (A7/3). The contents of the message and the value of cycle limiter differs depending on the software version. It can be for example: “Brake defective stop vehicle”.