End of line volume learn sequence of friction element fill volumes for

Abstract

The present invention provides improved initial shift quality in an electronically controlled automatic transmission by enabling the friction element fill volumes to be 'learned' by the transmission controller before the vehicle leaves the assembly line. An end of line (EOL) volume learn procedure is intended for final check out at car assembly or for other appropriate circumstances such as for service after a transaxle has been rebuilt or replaced, or as a diagnostic tool to help confirm an indicated condition of an element. Upon satisfaction of a set of initial conditions, an end of line volume learn procedure is initiated wherein the transmission is cycled through a number of phases, each phase generally corresponding to the application of a different friction element. In other words, each element is applied or logically turned 'ON' until a predetermined change in the amount of separation between engine speed and turbine speed (slip) is identified, thereby indicating the apply point of the respective element. Various parameters are measured as each element is applied and released, these parameters being used to calculate an initial fill volume. The initial fill volume of each element is stored in RAM memory for use by the transmission controller when the vehicle is actually driven for the first time.