A method for operating a vehicle drive train comprising a drive unit, a transmission, and an all-wheel splitter having a clutch. The all-wheel splitter is positioned between the transmission and the output and splits a transmission output torque to vary the torque distribution to driven axles of the output. The split of the output torque to the driven axles is performed by a control unit in such a way that the transmission output torque, less a predetermined nominal torque set by the all-wheel drive strategy, is transferred to a first axle while the nominal torque is transferred to a second axle. When defined operating conditions are met, a clutch monitoring function is activated and the nominal torque is replaced by a torque definition of the clutch monitoring function so that the torque which is transferred by clutch to the second driven axle, is increased, then kept constant, and thereafter reduced.