Abstract: A control system for a hydraulic automatic transmission includes a fault detection module and a transmission diagnostic module. The fault detection module detects faults of components of the transmission, wherein the faults may indicate low hydraulic fluid pressure in the transmission or failure of one or more of the components. The transmission diagnostic module determines whether the faults are due to low hydraulic pressure based on the detected faults, a predetermined number of faults, and a plurality of conditions.

Abstract: A system and method for selectively engaging and disengaging auxiliary equipment to avoid gear clash in a vehicle is disclosed. The system includes a transmission, a transfer case, and a transmission controller. The transmission has a plurality of gears and the transfer case is coupled to the transmission by an output shaft. The controller includes control logic for controlling the engagement and disengagement of the auxiliary equipment. The control logic has a first control logic for determining whether an operator has actuated a selector switch, a second control logic for actuating a torque transmitting device to engage or disengage the auxiliary equipment and avoid gear clash, a third logic for monitoring the engagement or disengagement of the auxiliary equipment, and a fourth control logic determining whether the auxiliary equipment has been engaged or disengaged.

Abstract: A system and method for selectively engaging and disengaging auxiliary equipment to avoid gear clash in a vehicle is disclosed. The system includes a transmission, a transfer case, and a transmission controller. The transmission has a plurality of gears and the transfer case is coupled to the transmission by an output shaft. The controller includes control logic for controlling the engagement and disengagement of the auxiliary equipment. The control logic has a first control logic for determining whether an operator has actuated a selector switch, a second control logic for actuating a torque transmitting device to engage or disengage the auxiliary equipment and avoid gear clash, a third logic for monitoring the engagement or disengagement of the auxiliary equipment, and a fourth control logic determining whether the auxiliary equipment has been engaged or disengaged.

Abstract: A system and method for selectively engaging and disengaging auxiliary equipment to avoid gear clash in a vehicle is disclosed. The system includes a transmission, a transfer case, and a transmission controller. The transmission has a plurality of gears for establishing a plurality of gear ratios. The transfer case is coupled to the transmission by an output shaft. The transmission controller is in communication with a plurality of control devices for controlling the operation of the transmission. The controller includes control logic for controlling the engagement and disengagement of the auxiliary equipment.

Abstract: A control system for a hydraulic automatic transmission includes a fault detection module and a transmission diagnostic module. The fault detection module detects faults of components of the transmission, wherein the faults may indicate low hydraulic fluid pressure in the transmission or failure of one or more of the components. The transmission diagnostic module determines whether the faults are due to low hydraulic pressure based on the detected faults, a predetermined number of faults, and a plurality of conditions.

Abstract: A system and method for selectively engaging and disengaging auxiliary equipment to avoid gear clash in a vehicle is disclosed. The system includes a transmission, a transfer case, and a transmission controller. The transmission has a plurality of gears for establishing a plurality of gear ratios. The transfer case is coupled to the transmission by an output shaft. The transmission controller is in communication with a plurality of control devices for controlling the operation of the transmission. The controller includes control logic for controlling the engagement and disengagement of the auxiliary equipment.

Abstract: A system and method for selectively engaging and disengaging auxiliary equipment to avoid gear clash in a vehicle is disclosed. The system includes a transmission, a transfer case, and a transmission controller. The transmission has a plurality of gears for establishing a plurality of gear ratios. The transfer case is coupled to the transmission by an output shaft. The transmission controller is in communication with a plurality of control devices for controlling the operation of the transmission. The controller includes control logic for controlling the engagement and disengagement of the auxiliary equipment.

Abstract: A method of detecting and preventing tie-up during a double transition shift of an automatically shiftable transmission operatively connected with an engine is provided. The method includes. A) shifting the automatically shiftable transmission from an initial speed ratio to an intermediate speed ratio; B) commanding the automatically shiftable transmission to shift from the intermediate speed ratio to a final speed ratio; D) determining if the automatically shiftable transmission has been operating in the intermediate speed ratio for greater than a predetermined amount of time after commanding the automatically shiftable transmission to shift from the intermediate speed ratio to the final speed ratio; and E) preventing shifting from the intermediate speed ratio to the final speed ratio to avoid tie-up if it is determined that the automatically shiftable transmission has been operating in the intermediate speed ratio for greater than a predetermined amount of time.

Abstract: A method of detecting and preventing tie-up during a double transition shift of an automatically shiftable transmission operatively connected with an engine is provided. The method includes. A) shifting the automatically shiftable transmission from an initial speed ratio to an intermediate speed ratio; B) commanding the automatically shiftable transmission to shift from the intermediate speed ratio to a final speed ratio; D) determining if the automatically shiftable transmission has been operating in the intermediate speed ratio for greater than a predetermined amount of time after commanding the automatically shiftable transmission to shift from the intermediate speed ratio to the final speed ratio; and E) preventing shifting from the intermediate speed ratio to the final speed ratio to avoid tie-up if it is determined that the automatically shiftable transmission has been operating in the intermediate speed ratio for greater than a predetermined amount of time.

Abstract: A system and method for selectively engaging and disengaging auxiliary equipment to avoid gear clash in a vehicle is disclosed. The system includes a transmission, a transfer case, and a transmission controller. The transmission has a plurality of gears for establishing a plurality of gear ratios. The transfer case is coupled to the transmission by an output shaft. The transmission controller is in communication with a plurality of control devices for controlling the operation of the transmission. The controller includes control logic for controlling the engagement and disengagement of the auxiliary equipment.

Abstract: A method for determining the condition of a transmission fluid filter and controlling an operator indicator to alert the operator that the fluid filter requires replacement is disclosed. The method includes monitoring a fluid pressure switch, determining an operating mode of the transmission, determining whether the operating mode of the transmission is changing, activating a timer if the operating mode is changing, recording the time, comparing the time to a predefined time threshold, determining whether the recorded time is greater than the predefined threshold, and activating the operator indicator to indicate that the fluid filter requires replacement if the recorded time is greater than the predefined threshold.

Abstract: A method for determining the condition of a transmission fluid filter and controlling an operator indicator to alert the operator that the fluid filter requires replacement is disclosed. The method includes monitoring a fluid pressure switch, determining an operating mode of the transmission, determining whether the operating mode of the transmission is changing, activating a timer if the operating mode is changing, recording the time, comparing the time to a predefined time threshold, determining whether the recorded time is greater than the predefined threshold, and activating the operator indicator to indicate that the fluid filter requires replacement if the recorded time is greater than the predefined threshold.

Abstract: The present invention provides a method and apparatus for a self cleaning logic valve assembly. The logic valve assembly is adapted to cycle and thereby clean itself in response to one or more predefined parameters which are programmed into a programmable controller. The logic valve assembly is additionally configured to cycle according to one or more of several different methods which have been shown to efficiently clean the valve assembly. The cleaning process takes place during a predetermined time period selected to avoid causing an unwanted gear speed ratio change of the vehicle transmission. In this manner, the logic valve assembly may be automatically cleaned while the vehicle is being driven and without interfering with vehicle operation such that the valve cleaning is imperceptible to the operator.

Abstract: The present invention provides a method and apparatus for a self-cleaning valve assembly. The valve is adapted to cycle and thereby clean the valve assembly in response to one or more predefined parameters which are programmed into a programmable controller. The valve is additionally configured to cycle according to one or more of several different methods which have been shown to efficiently clean the valve assembly. In this manner, the valve assembly is automatically cleaned improving the efficiency thereof and eliminating stuck valve warranty returns.

Abstract: An improved method of operation for a motor vehicle automatic transmission determines a vehicle speed for purposes of selecting a desired transmission gear at least in part based on the wheel speeds of the vehicle. If the vehicle is being operated in a two-wheel drive mode, the vehicle speed is determined based on an average of the speeds of the un-driven wheels; if the vehicle is being operated in a four-wheel drive mode, the vehicle speed is determined based on the lowest of the four wheel speeds. Optionally, the wheel speeds are only used to determine vehicle speed if the Reverse range of the transmission has been engaged within a specified time interval, and otherwise the vehicle speed is determined based on an output speed of the transmission.

Abstract: An improved downshift control for an automatic transmission optimized for sequential shifting achieves skip-downshifting to a target gear by shifting the transmission to neutral and controlling the engine output torque while the transmission is reconfigured to establish the target speed ratio. The engine torque control is designed to allow the transmission input speed to reach the synchronization speed for the target speed ratio at a desired time, and the shift is completed when the transmission input speed actually reaches the synchronization speed. The engine torque control is predicated on a modeled engine torque parameter, and the torque control includes an adaptive parameter for adaptively adjusting the torque control to ensure that the input speed reaches the synchronization speed at the desired time.

Abstract: An improved method of operation for a motor vehicle automatic transmission determines a vehicle speed for purposes of selecting a desired transmission gear at least in part based on the wheel speeds of the vehicle. If the vehicle is being operated in a two-wheel drive mode, the vehicle speed is determined based on an average of the speeds of the un-driven wheels; if the vehicle is being operated in a four-wheel drive mode, the vehicle speed is determined based on the lowest of the four wheel speeds. Optionally, the wheel speeds are only used to determine vehicle speed if the Reverse range of the transmission has been engaged within a specified time interval, and otherwise the vehicle speed is determined based on an output speed of the transmission.

Abstract: An improved downshift control for an automatic transmission optimized for sequential shifting achieves skip-downshifting to a target gear by shifting the transmission to neutral and controlling the engine output torque while the transmission is reconfigured to establish the target speed ratio. The engine torque control is designed to allow the transmission input speed to reach the synchronization speed for the target speed ratio at a desired time, and the shift is completed when the transmission input speed actually reaches the synchronization speed. The engine torque control is predicated on a modeled engine torque parameter, and the torque control includes an adaptive parameter for adaptively adjusting the torque control to ensure that the input speed reaches the synchronization speed at the desired time.

Abstract: An improved diagnostic control method for a motor vehicle powertrain including an electronically controlled multi-range transmission and a multi-range transfer case, wherein a default determination of transfer case range enables reliable evaluation of transmission ratio, for powertrain configurations with or without a transfer case range indicator switch. An overall speed ratio is computed according to a ratio of the transmission input speed and the transfer case output speed, and the computed ratio is monitored to identify a period of stable operation at the conclusion of transmission shifting and in steady state operation during which the rate of change of the computed ratio is stable over a predefined interval. If the computed ratio is also deemed to be stable, it is compared with an expected overall ratio based on an assumed speed range (low or high) of the transfer case.

Abstract: An electro-hydraulic control mechanism for use with a multi-speed transmission includes a pair of logic valves, which are manipulated during the ratio interchanges and the ratio establishment by aiding in the distribution of fluid pressure from a plurality of trim valves. The logic valves are retained in specific drive ranges in the event of electrical discontinuance.