Abstract: An electronic control system for a multiple ratio automotive transmission having pressure operated clutch and brake servos for controlling ratio changes, solenoid operated valves for triggering operation of shift valves in a valve circuit that communicates with the servos, a microprocessor for developing control signals in response to input variables that measure engine torque, engine speed, vehicle speed and a driver-actuated range selector, the shift valves responding to the control signals in accordance with a control strategy that effects controlled response of the shift valves to meet varying road speed, engine torque and road conditions with high quality shift performance.

Abstract: A control for a hydrokinetic torque converter lockup clutch having a clutch plate that cooperates with a torque converter impeller shell to define a control pressure cavity wherein the clutch plate is subjected to the pressure in the torus circuit of the torque converter and wherein an electronically controlled valve system is used to modulate the pressure in the control pressure cavity thereby varying the clutch capacity to establish a controlled degree of slip of the clutch so that the actual slip of the clutch may be maintained at a target slip value which is adjusted depending upon the value of input shaft speed data and throttle position data stored in the memory of a microprocessor, the microprocessor being designed to calibrate a desired slip value for each engine torque and turbine speed condition whereby a closed-loop electronic control may be achieved to provide a partial converter bypass during the major portion of the vehicle operating time.