A fault diagnosis procedure for detecting faulty components in a vehicle, wherein, for at least one identifiable fault cause of a faulty component, a
system parameter of the vehicle that is influenced by the fault cause is determined and compared with a target value of the
system parameter, and a determined
signal deviation between the determined
system parameter and the target value of the system parameter is compared with a stored fault characteristic
signal deviation, and if the determined
signal deviation matches the fault characteristic signal deviation, the fault cause and / or faulty component associated with the fault characteristic signal deviation is uniquely identified, wherein the entire development process for the fault diagnosis procedure essentially consists of the following six individual steps, which are executed sequentially: - Selection of faults to be diagnosed, whereby in this first step the various components of the vehicle are analyzed in such a way that the possible causes of faults are listed for each component; -
Structural analysis, whereby in this second step it is checked whether there is a possibility in principle of model-based diagnostics of the system; - Creation of a nominal model, whereby in this third step, so-called nominal models are created for those
system parameters that are used and evaluated for the identification of a faulty system component, in which a normal operation of the system component is depicted; -
Sensitivity analysis, in which, in this fourth step, defined causes of failure are imprinted into the system and their effects on the relevant system size(s) are considered using the nominal model, thereby identifying a unique assignment of a cause of failure or a faulty system component to its effect on the relevant system size; - Creation of fault models, whereby in this fifth step the knowledge about the effect is stored in a reference source onboard in the vehicle, whereby, based on this reference source, a statement can be made at any time valid for the diagnosis as to whether this cause of fault is present or not and - Integration into a
diagnostic system, whereby in this sixth step the developed diagnostic procedure is transferred to a corresponding
target control unit in the vehicle.