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A method for the calibration or diagnosis of a motor vehicle brake system having a cyclically operated pump. At least one parameter (URPOff), representing the electromotor force of the reference pump, is repeatedly ascertained during operation of a reference pump under defined guidelines. A statisti

A method for the calibration or diagnosis of a motor vehicle brake system having a cyclically operated pump. At least one parameter (URPOff), representing the electromotor force of the reference pump, is repeatedly ascertained during operation of a reference pump under defined guidelines. A statistical characteristic variable (URPOff) is derived from the values of parameter (URPOff) ascertained for the reference pump. Parameter (UBPOff) is ascertained under a corresponding guideline during operation of an operating pump. Corresponding statistical characteristic variable (UBPOff) is derived from the values of parameter (UBPOff) ascertained for the operating pump. At least one ratio number is calculated 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) calculated for the reference pump and the characteristic variable (UBPOff) calculated for the operating pump.

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1. 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 metho

1. 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); anddetermining, 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. 2. The method of claim 1, wherein with the aid of said at least one ratio, a characteristic curve (pv(UBPOff)) of the operating pump is adapted to a characteristic curve (pv(URPOff)) correspondingly prescribed for the reference pump. 3. The method as claimed in claim 2, wherein the characteristic curves (pv(URPOff), pv(UBPOff)) represent a functional relationship between the at least one voltage (UOff) and a brake line pressure (pv) of the motor vehicle brake system, a pumping rate of the pump and/or the temperature of the pump. 4. The method as claimed in claim 1, wherein if said at least one ratio lies outside a prescribed tolerance range, the operating pump is identified as defective. 5. The method as claimed in claim 1, wherein the statistical characteristic variables (URPOff, UBPOff) are determined from a histogram (HURPOff, HUBPOff) of a voltage (UOff) created for the reference pump and for the operating pump, respectively. 6. The method as claimed in claim 5, wherein the statistical characteristic variables (URPOff, UBPOff) are determined from one or more of the following parameters: a last voltage value (UOnL) of a pulse of an operating clock of the respective pump,a first voltage value (UOnF) of the pulse,a first voltage value (UOff) of an interpulse period following the pulse,a differential value (UFall) between the last voltage value (UOnL) of the pulse and the first voltage value (UOff) of the interpulse period,a lowest voltage value (UMin) within the interpulse period,a sum (USum) of the voltage values within the interpulse period,a mean voltage value (UAver) of the voltage values within the interpulse period,a slope (USlope) of the voltage fall within the interpulse period,a difference (URise) between the lowest voltage value (UMin) of the interpulse period and the first voltage value (UOnF) of the following pulse, anda time (tFall) up to the fall of the voltage to zero. 7. The method as claimed in claim 1, wherein within the scope of the stipulations, an operating clock of the respective pump is prescribed during the measurement. 8. The method as claimed in claim 1, wherein the at least one voltage (UOff) is normalized. 9. The method as claimed in claim 1, wherein use is made, as a statistical characteristic variable, of the mean value (URPOff, UBPOff) of the values of the voltage (UOff) that are acquired for the reference pump and for the operating pump, respectively. 10. The method as claimed in claim 1, wherein a mathematical distribution function (G) is adapted to each histogram (HURPOff, HUBPOff). 11. The method as claimed in claim 10, wherein the mathematical distribution function (G) is a Gaussian distribution function. 12. The method as claimed in claim 1, wherein a plurality of ratios are calculated in order to form a total ratio. 13. The method as claimed in claim 12, wherein the total ratio is a weighted sum of the ratios. 14. A system 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 device comprising: a reference processor configured to: repeatedly determine 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;derive a statistical characteristic variable (URPOff) from the voltage (URPOff);an operating processor configured to: determine 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;derive a corresponding statistical characteristic variable (UBPOff) from the voltage (UBPOff);calculate 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); anddetermine if the operating pump in the motor vehicle is defective by comparing the at least one ratio to a tolerance range.