Method for operating a vehicle drive train

A method for operating a vehicle drivetrain (1), the vehicle drivetrain (1) having a drive machine (2), an output (3) and a gearbox (4), the gearbox (4) arranged in power flow between the drive machine (2) and the output (3), the gearbox (4) having at least with one positively engaging shift element (A, F) and a plurality of frictionally engaging shift elements (B, C, D, E), the at least one positively engaging shift element (A, F) and the plurality of frictionally engaging shift elements (B, C, D, E) selectively closable in order to realize different transmission ratios (“1” to “R”) of the gearbox (4), only some of the transmission ratios (“1” to “R”) realizable with the at least one positively engaging shift element (A, F), the vehicle drivetrain (1) configured such that, in the presence of a demand for activation of an engine start-stop function of the vehicle drivetrain (1), the drive machine (2) is decoupled from the output (3), the drive machine (2) is shut down, and the at least one positively engaging shift element (A, F) is transferred into or kept in a closed operating state of the at least one positively engaging shift element (A, F), the method comprising:

• opening, in the presence of a demand for activation of a sailing operating function of the vehicle drivetrain (1) and a simultaneously activated engine start-stop function, the closed positively engaging shift element (F) while the drive machine (2) is left both decoupled from the output (3) and shut down.