A shift range switching system includes: a motor that includes a motor winding and generates a cogging torque by a permanent magnet; a drive circuit; an output shaft; a shift range switching mechanism that includes a trough providing member with troughs and crests and integrally rotates with the output shaft, an engagement member that fits in one trough corresponding to a shift range, and an urging member that urges the engagement member toward the one trough; and a control unit. The engagement member drops into the one trough with an allowance. When an abnormality occurs in a motor drive system in an ascending action in which the engagement member moves from one trough toward one crest, the shift range switching system reduces an occurrence probability of an intermediate range stop abnormality.

A control apparatus of a transmission includes the transmission that is configured to perform shifting operation with use of a control pressure derived from an actuating oil to be supplied to a hydraulic pressure unit. The control apparatus includes a hydraulic pressure supply source, a switcher, a control pressure adjusting valve, an abnormality detector, and a controller. The controller is configured to control the shifting operation of the transmission to keep a revolution speed of an engine, in an abnormal period in which an abnormality of the switcher is detected by the abnormality detector, at a value that is equal to or greater than an abnormal lower limit value. The abnormal lower limit value is higher than a normal lower limit value in a normal period. The normal period is prior to the detection of abnormality of the switcher by the abnormality detector.

A shift range control device includes a drive circuit, a voltage detector, and a controller. The drive circuit includes switching elements, and is shared by a plurality of winding sets. The voltage detector detects terminal voltages of respective phases. The controller controls energization of the winding sets by controlling on and off operations of the switching elements, and controls interruption units each capable of switching between conduction and interruption of power from a power supply to a corresponding winding set. The controller performs disconnection diagnosis based on the terminal voltage during energization of the winding sets in a control state where one of the interruption units is controlled to conduct the power and a remaining interruption unit is controlled to interrupt the power.

In a transmission control device for controlling a transmission, a controller determines failure of a SOL corresponding to a hydraulic secondary-pressure actuator. The controller variably controls line command pressure, and in a case where the failure is determined, fixes the line command pressure to a line pressure set value. The controller variably controls primary command pressure, and in a case where the failure is determined, continuously changes a speed ratio of a variator by variably controlling the primary command pressure. The controller variably controls secondary command pressure, and in a case where the failure is determined, fixes the secondary command pressure to a secondary pressure set value.

In a transmission control device for controlling a transmission, a controller determines failure of a SOL corresponding to a hydraulic primary-pressure actuator. The controller variably controls line command pressure, and in a case where the failure is determined, continuously changes a speed ratio of a variator by variably controlling the line command pressure. The controller variably controls primary command pressure, and in a case where the failure is determined, fixes the primary command pressure to a primary pressure set value. The controller variably controls secondary command pressure, and in a case where the failure is determined, fixes the secondary command pressure to a secondary pressure set value.

An actuation unit has a primary motor and a transmission mechanism for transmitting motion generated by the primary motor to a control member. The transmission mechanism includes a first transmission member connected to a drive shaft of the primary motor, a second transmission member drivingly connected to the control member, and a coupling member shiftable between an engagement position and a disengagement position. The transmission mechanism further includes a first elastic member interposed between the first transmission member and the second transmission member to cause rotation of the second transmission member relative to the first transmission member when the coupling member is in the disengagement position, a second elastic member for elastically urging the coupling member towards the engagement position, and an auxiliary actuation device for shifting the coupling member from the engagement position to the disengagement position.

A failure judgment device of an automatic transmission includes: a first abnormality judging section configured to judge a power supply fault abnormality or a breaking abnormality of the solenoid, from a selected shift stage and a state of the transmission mechanism, after the detection of the electric abnormality; and a second abnormality judging section configured to judge the power supply abnormality or the breaking abnormality of the solenoid, from the monitor current value when the solenoid valve is switched to an OFF state, after the detection of the electric abnormality, when one of the first abnormality judging section and the second abnormality judging section judges the power supply fault abnormality or the breaking abnormality, the judgement result being outputted.

An electronic transmission range select actuator (ETRSA) includes two independent drive systems that are each able to actuate a common shaft, for example an output shaft of the ETRSA, via a coupling device disposed between and connecting the gear trains of each system. The first drive system of the two independent drive systems is used during normal vehicle operation to change the transmission gear range to a desired gear range. The second drive system is used in case of abnormal operation of the first drive system to return the vehicle transmission to the park transmission range.

A transmission includes an input shaft that couples to a prime mover, twin countershafts and a main shaft having gears coupled thereon, an output shaft that selectively provides a torque output to a driveline, a first shift actuator that selectively couples the input shaft to the main shaft. The transmission includes a second shift actuator that couples the main shaft to the output shaft with a selected reduction ratio, and a controller including a vehicle state circuit that interprets at least one vehicle operating condition, and a neutral enforcement circuit that provides a first neutral command to the first shift actuator and a second neutral command to the second shift actuator, in response to the at least one vehicle operating condition indicating that vehicle motion is not intended.

A method for controlling internal electronic range selection for an automatic transmission includes: confirming if a range change command has been ordered from a current transmission operating state; verifying expected performance from at least first and second mode valves and a park servo are present in the current transmission operating state prior to allowing a range change event; during the range change event: generating proactive commands including ordering a reduction in a hydraulic system pressure; and identifying if an unexpected event is detected; and following completion of the range change event confirming expected performance is obtained from at least the first and second mode valves and the park servo to achieve a driver intended state.