A method of operating a motor vehicle having a drive aggregate, a transmission and a hydraulic system. The transmission has shift elements and, for each gear, only a portion of the elements are engaged while a remainder are disengaged. The hydraulic system has main pump driven by the drive aggregate and an auxiliary pump. The method tests the functionality of the auxiliary pump. The drive aggregate and the main pump are insufficiently driven such that the shift elements can not engage. The auxiliary pump is driven to provide required pressure such that all but one of the shift elements fully engages. The remaining shift element is then first engaged up to its engagement point and then either engaged beyond its engagement point or another unengaged shift element is engaged beyond its engagement point. The functionality of the auxiliary pump is determined based on changes in the drive aggregate's rotational speed.