Fault-detection methods for motor vehicle gearboxes

Method for detecting a fault state in an automated drive train of a motor vehicle, which drive train has a drive unit, at least one friction clutch whose input is connected to an engine shaft, and a multi-step gearbox having at least one drive shaft which is connected to an output of the clutch, having the steps:

• sensing whether the at least one clutch is at least partially closed;
• sensing an output shaft rotational speed of the multi-step gearbox, and
• sensing at least one further parameter, selected from the rotational speed of the engine shaft, the rotational speed of the at least one drive shaft, the position of the at least one clutch and of the torque transmitted via the at least one clutch, and
• logic combination of the output shaft rotational speed with the further parameter, and comparison of the logic combination with a reference value, in order to detect the fault state.

Method for detecting a fault state in an automated motor vehicle gearbox, in which method driving torque can be transmitted to at least one driven wheel via a first and a second parallel branch, wherein a clutch is provided in each branch, having the steps:

• sensing of the torque transmitted via the first clutch;
• sensing of the torque transmitted via the second clutch;
• sensing whether a gear speed is engaged in both branches;
• and
• detection of a fault state if a gear speed is engaged in both branches and if a sum of the torques transmitted via the first and second clutches is greater than a reference value.