Abstract: A power transmission system includes an engine-driven lockup type torque converter for driving a gear shift mechanism shiftable to different speed ranges by solenoid operated clutch valves. A digital electronic controller provides output signals to operate the solenoids of the clutch valves. The controller receives input signals from a manually operable multiposition electric shift range selector switch; from an output speed sensor on the gear shift mechanism; and from an engine throttle position (on-off) switch.The controller comprises a counter circuit regulated by a system clock, for receiving amplified and shaped pulses from the speed sensor and for providing a counter signal related to gear shift mechanism output speed. The counter signals from the counter are presented to a speed matrix and signal pattern recognition circuits connected to the matrix ascertain whether certain speeds are reached.