Control strategy for hydraulically-switched engine mechanisms

A method for distributing lock pin ejections evenly over all the switchable mechanisms in a plurality of switchable mechanisms: establishing a limiting number of lock pin ejections; designating a primary switchable mechanism for the mode change upon command from an engine control module (ECM); employing the designated primary switchable mechanism until the limit is reached; designating another switchable mechanism a primary; employing the second primary mechanism until the limit is reached again; and designating sequentially each of the remaining switchable mechanisms as primary switchable mechanisms, each until the limit is reached again. The ECM counts the activation commands and switches the primary designation when the limit is reached so that each mechanism has the same exposure to ejections, and the number of ejections per mechanism is evenly distributed. If ejection detection means is available, the ECM may accumulate actual ejections for each mechanism and schedule the primary designation change thereupon.