Patent ID: 7909733

Claim:
A method of controlling a transmission having a plurality of hydraulic clutches for shifting between one or more transmission ratios, the method comprising: determining to execute a shift of the transmission between a first ratio associated with an off-going hydraulic clutch of the transmission, which is currently engaged, and a second ratio associated with an on-coming hydraulic clutch of the transmission, which is currently disengaged; commanding a decrease of hydraulic pressure to the off-going hydraulic clutch to begin disengagement of the off-going hydraulic clutch; commanding a flow of hydraulic fluid to the on-coming hydraulic clutch to fill a clutch chamber of the on-coming hydraulic clutch via a clutch fill pressure command; detecting a pressure spike greater than a predetermined magnitude in the chamber of the on-coming hydraulic clutch; and determining based on the detected pressure spike that the clutch chamber is filled, and thereafter initiating a clutch modulation phase to fully engage the on-coming hydraulic clutch, whereby the on-coming hydraulic clutch is able to fully accept torque transferred from the off-going hydraulic clutch.