A control device for an automatic transmission includes: a failure diagnosis section for diagnosing whether or not a failure has occurred in a shift control system of the automatic transmission; a fail-safe control section for fixing the automatic transmission into a predetermined gear position in response to confirmation of the failure of the shift control system of the automatic transmission; and an oil temperature rise regulation torque reduction control section for outputting a torque reduction request to suppress torque of a vehicle driving source, based on temperature of transmission operating oil of the automatic transmission, and outputting the torque reduction request in response to satisfaction of an oil temperature condition that is set lower in oil temperature when the automatic transmission is fixed in a first gear position by the fail-safe control section than when the automatic transmission is not fixed in the first gear position.

A control device for an automatic transmission includes: a failure diagnosis section for diagnosing whether or not a failure has occurred in a shift control system of the automatic transmission; a fail-safe control section for fixing the automatic transmission into a predetermined gear position in response to confirmation of the failure of the shift control system of the automatic transmission; and an oil temperature rise regulation torque reduction control section for outputting a torque reduction request to suppress torque of a vehicle driving source, based on temperature of transmission operating oil of the automatic transmission, and outputting the torque reduction request in response to satisfaction of an oil temperature condition that is set lower in oil temperature when the automatic transmission is fixed in a first gear position by the fail-safe control section than when the automatic transmission is not fixed in the first gear position.

In an apparatus for controlling an automatic transmission connected to a prime mover mounted on a vehicle, having a torque converter equipped with a lock-up clutch, when predetermined operating conditions of the vehicle are satisfied at drive-off, a lock-up clutch engaging circuit is formed through a hydraulic supply circuit. Next it is determined whether engage-position sticking malfunction of the lock-up clutch has occurred based on a ratio of an input rotational speed of the automatic transmission relative to an output rotational speed of the prime mover and a change rate of the output rotational speed of the prime mover when the lock-up clutch engaging circuit has been formed, and fail-safe control is then implement when the sticking is determined.

In an apparatus for controlling an automatic transmission connected to a prime mover mounted on a vehicle, having a torque converter equipped with a lock-up clutch, when predetermined operating conditions of the vehicle are satisfied at drive-off, a lock-up clutch engaging circuit is formed through a hydraulic supply circuit. Next it is determined whether engage-position sticking malfunction of the lock-up clutch has occurred based on a ratio of an input rotational speed of the automatic transmission relative to an output rotational speed of the prime mover and a change rate of the output rotational speed of the prime mover when the lock-up clutch engaging circuit has been formed, and fail-safe control is then implement when the sticking is determined.

A method for operating an automatic transmission apparatus having a parking lock device. The parking lock device has a hydraulic apparatus with a hydraulic cylinder and a hydraulic piston arranged therein, which can be placed in at least two positions by a lock apparatus and an emergency unlock apparatus. The hydraulic piston is operatively connected to a shifting shaft of the parking lock device, and a pressure can be adjusted in the hydraulic cylinder by a hydraulic valve. The shifting shaft can be shifted within an operating position range by the hydraulic apparatus. In doing so, upon activation of the emergency unlock apparatus, the shifting shaft is shifted into a position that is outside of the operating position range, and an operating state of the emergency unlock apparatus is checked.

This hydraulic pressure warning device 100 issues a hydraulic pressure warning when an anomalous hydraulic pressure drop or clogging of an oil filter 101 has been estimated to be occurring. The hydraulic pressure warning device is provided with a control device 103 that: executes control so that a first hydraulic pressure warning is issued if an anomalous hydraulic pressure drop has been estimated to be occurring; and executes control so that a second hydraulic pressure warning is issued if clogging of the oil filter 101 has been estimated to be occurring.

An automatic transmission where the control portion controls the adjustment solenoid valve so that the circulation hydraulic pressure equals to a second circulation hydraulic pressure higher than the first circulation hydraulic pressure when the rotational speed difference between the output rotational speed of the fluid transmission device and the rotational speed of the driving source is more than the predetermined rotational speed.

A control circuit controls driving of a motor to switch over a shift range. A target rotation speed setting part sets a target rotation speed of the motor. A rotation speed detection part detects a present rotation speed, which is an actual rotation speed, of the motor. A rotation speed error calculation part calculates a rotation speed error, which is an error between the target rotation speed and the present rotation speed. A request torque calculation part calculates a request torque for the motor based on the rotation speed error. A phase lead correction value calculation part calculates a phase lead correction value of a current supply phase relative to a rotation phase of a rotor of the motor based on the request torque.

A control circuit controls driving of a motor to switch over a shift range. A target rotation speed setting part sets a target rotation speed of the motor. A rotation speed detection part detects a present rotation speed, which is an actual rotation speed, of the motor. A rotation speed error calculation part calculates a rotation speed error, which is an error between the target rotation speed and the present rotation speed. A request torque calculation part calculates a request torque for the motor based on the rotation speed error. A phase lead correction value calculation part calculates a phase lead correction value of a current supply phase relative to a rotation phase of a rotor of the motor based on the request torque.

A PWM control part rotationally drives a motor based on a PWM control value. A rotation speed control part controls a rotation speed of the motor. A rotation angle detection part detects a rotation angle of the motor. A reference position learning part controls the motor to rotate at a constant rotation speed until a detent plate stops at a limit position of a movable range and learns a reference position of the motor. A current detection circuit detects a current value corresponding to a driving current. A current limitation part limits a current supplied to the motor. A PWM control value limitation part controls the PMW control value to be equal to or smaller than a PWM limitation value, which is a predetermined value. A relation check part checks whether a relation between a current value detected by the current detection circuit and the PWM control value is inappropriate.