Abstract: A method of in-gear tolerance (IGT) control continuously calculates the magnitude to slip or IGT to be used during a shift. The method calculates the indicated slip while the transmission is in-gear conditions and then freezing the current value for use when a shift is initiated.

Abstract: A fluid actuated switch valve in a four-speed transmission to direct fluid flow between solenoid-actuated valves and a clutch apply piston in a low gear position and in a high gear position, while allowing one of the solenoid-actuated valves to also direct fluid flow to the lock-up piston of a torque converter in the high gear position.

Abstract: A method of reducing stall torque from the engine to the transmission based on a desired engine speed to minimize the potential interference and possible damage to any of the electronically controlled transmission components for an automatic transmission.

Abstract: A method of monitoring an output and adjusting the action affecting the output continuously for an electronic automatic transmission system wherein a controller is programmed to "learn" from the results of its operation. The method includes monitoring the speed of an input member and the instantaneous fluid volume of a friction element. The method also includes setting a learned volume value equal to an instantaneous fluid volume whenever the input speed is within a predetermined range of a predetermined speed. The method further includes comparing the learned volume value to a stored fill volume value at the end of the shift and adjusting the stored fill volume value based on the difference between the learned volume value and the stored fill volume value.

Abstract: A method of reducing the shift torque from the engine to the automatic transmission system in response to predetermined conditions existing in the transmission so as to minimize the potential interference and possible damage to any of the electronically controlled transmission components.

Abstract: A method of torque phase shift control for an electronic automatic transmission system to determine the apply rate of a fluid actuating device and adjusts the same to match the torque build-up of the apply element to the torque fall-off of the release element during shifting of the transmission.

Abstract: Pressure balanced pistons in a four-speed automatic transmission which prevent the centrifugal force acting on the rotating fluid in the clutch cavity from causing the piston to remain in the clutch applied position even though the fluid apply line is vented.

Abstract: A method of determining the shift lever position of an electronic automatic transmission system by identifying the mode of transmission operation selected by the driver of the vehicle to provide hysteresis between the park, reverse, neutral, overdrive, drive and low positions and to permit limited operation of the controller without functioning PRNODDL sensors.

Abstract: A method of adaptively idling a transmission in an electronic automatic transmission system putting the transmission to "neutral" when the engine is idling and the brakes are applied.

Abstract: A method for controlling the apply element during a kickdown shift for an electronic automatic transmission system by controlling the turbine speed along a desired slope to adaptively predict how much time remains to fill the apply element after having achieved a predetermined target speed for the turbine.

Abstract: A method of sensing and determining open circuits and short circuits to the solenoid-actuated valves for the electronic automatic transmission.

Abstract: A method of reverse clutch operation prevents excessive wear of the reverse clutch in a four-speed automatic transmission by venting one clutch, filling the reverse clutch and applying it, and filling and reapplying the one clutch.

Abstract: A method of determining the continuity of solenoids in an electronic automatic transmission system wherein a controller is programmed to determine solenoid continuity by checking for the presence of an inductive "OFF" spike which results from an open circuit or a direct short to supply voltage from the solenoid of the solenoid-actuated valves.

Abstract: A method of adaptively scheduling a shift or inhibiting a shift until engine speed is at least equal to or greater than the output speed of the target gear which will prevent any negative torque, and will eliminate any "clunk" in the drivetrain in an automatic transmission system.

Abstract: A fluid actuated switch valve is provided in a four-speed transmission to direct fluid flow between solenoid-actuated valves and a clutch apply piston in a low gear position and in a high gear position, while allowing one of the solenoid-actuated valves to also direct fluid flow to the lock-up piston of a torque converter in the high gear position.

Abstract: A method of shift selection in an electronic automatic transmission wherein a controller is capable of selecting between various desired transmission gear changes or shift patterns to place the transmission in the appropriate gear based on a plurality of input conditions. The method includes comparing a mask with a byte in a table row and determining whether a matching row was found. The method also includes pointing to the next row if a matching row was found and determining whether the present operating gear equals the next byte. The method further includes selecting the next byte to perform a predetermined gear change or selecting another byte to perform another predetermined gear change based on the present operating gear equaling the next byte, and executing the gear change selected.

Abstract: A method of determining the fluid temperature of an automatic transmission wherein a controller is programmed to determine the transmission temperature based on ambient and/or engine coolant temperatures and on observed transmission and engine warm-up rates. The controller may also be programmed to determine the transmission temperature based on the response of the pressure sensors provided.

Abstract: A method of controlling the speed change of a kickdown shift for an electronic automatic transmission system by predicting how much time remains to fill the apply element after having achieved a predetermined target speed for the turbine of the torque converter.

Abstract: A system which provides a vent reservoir to maintain a fluid level above the vent of the solenoid-actuated valves which ensures that the fluid passages are filled with fluid to provide rapid hydraulic response of the fluid system while allowing trapped air to automatically escape or vent.

Abstract: A solenois-actuated valve arrangement in a four-speed automatic transmission having a structure in combination with the manual valve in the hydraulic circuit that will enable a limp-home mode or limited transmission operation, which will permit the vehicle to operate in park, neutral, second or reverse gear as desired in that absence of electrical power to the solenoid-actuated valves.