A method of detecting substantial filling of a hydraulic cylinder of a hydraulically operated clutch of a vehicular transmission is disclosed and claimed. A pressure sensor disposed in a hydraulic line to the clutch cylinder provides a signal that the hydraulic pressure has dropped as the clutch cylinder begins to fill and also that the pressure has returned to a substantially normal level. The pressure sensor may be a continuously variable output such as an analog sensor, pulse width modulation (PWM) sensor, a similar device or, less desirably, a two state sensor. An iterative algorithm utilizes data from the sensor and a timer to determine when clutch fill is substantially complete.