Step-by-step variable transmission and method for controlling the same

A method for early detection of a fault in an automated step-by-step variable transmission, wherein, when a gear stage is already engaged, determining by monitoring and checking a plurality of parameters of the transmission as to whether an impermissible attempt is being carried out to engage a further gear stage, wherein the monitoring and checking step is made by:

• a) detecting whether the further gear stage is to be engaged by determining the actuation of a corresponding shift clutch of the gear stage,
• b) detecting an input actual variable which is substantially proportional to an input rotational speed of the step-by-step variable transmission, and an output actual variable which is substantially proportional to an output rotational speed of the transmission,
• c) checking as to whether a difference between a ratio of the input and the output actual variables and the transmission ratio which would be set up by the further gear stage is smaller for a predefined timespan, t2-t1, than a predefined tolerance range, wherein the predefined timespan prevents incorrect evaluations on account of a transient state, and
• d) determining a fault state if the difference does not lie within the tolerance range for the predefined timespan.