Abstract: A method of operating a transmission of a vehicle drive train is provided. The transmission comprises at least one interlocking shift element and at least one frictional shift element. The method comprises receiving a command for the at least one interlocking shift element to move to an engaged position, and applying a first pressure of fluid to the at least one interlocking shift element. The first pressure of fluid is less than a maximum engagement pressure. A second pressure of fluid to the at least one frictional shift element is pulsed. It is then determined whether the interlocking shift element has moved to the engaged position. The first pressure of fluid is then increased towards the maximum engagement pressure once it has been determined that the shift element is in the engaged position.