Method and device for the calibration or diagnosis of a motor vehicle brake system having a cyclically operated pump

A method for the calibration or diagnosis of a motor vehicle brake system having an operating pump operating in a pulsed fashion during which a pulse period for applying voltage to the operating pump and an interpulse period for not applying voltage to the operating pump are alternated, the method comprising:

• repeatedly determining, by a reference processor, during operation of a reference pump separate from the motor vehicle, under defined stipulations, at least a voltage (URPoff) generated by the reference pump during the interpulse period and representing the electromotive force of the reference pump;
• deriving, by the reference processor, a statistical characteristic variable (URPOff) from the voltage (URPoff);
• determining, by an operating processor, during operation of the operating pump in the motor vehicle, a voltage (UBPOff) generated by the operating pump during the interpulse period and representing the electromotive force of the operating pump under corresponding stipulations;
• deriving, by the operating processor, a corresponding statistical characteristic variable (UBPOff) from the voltage (UBPOff);
• calculating, by the operating processor, at least one ratio as a measure of the deviation of the operating behavior of the operating pump from the operating behavior of the reference pump from the characteristic variable (URPOff) and the characteristic variable (UBPOff);
• and
• determining, by the operating processor, if the operating pump in the motor vehicle is defective by comparing the at least one ratio to a tolerance range.