Fail determination device for vehicle automatic transmissions and control device for vehicle automatic transmissions

A control device for an automatic transmission of a vehicle which includes a transmission mechanism including frictional engagement element arranged to be engaged in accordance with a selected shift stage, and a solenoid valve arranged to control the engagement state of the frictional engagement element, the control device comprising:

• a failure judgement device including
• a control unit configured to
• monitor a current value which is an electrical value of current supplied to the solenoid valve;
• sense a generation of an electric abnormality of the solenoid valve from the monitored current value which is different from a command current value to the solenoid valve;
• judge a power supply fault abnormality which is a short circuit to a power supply, or a breaking abnormality, which is a disconnection, of the solenoid valve, from the selected shift stage and a state of the transmission mechanism, after a detection of the generation of the electric abnormality;
• and
• judge the power supply fault abnormality or the breaking abnormality of the solenoid valve, from the monitored current value when the solenoid valve is switched to an OFF state, after the detection of the generation of the electric abnormality,
• wherein the failure judgement device is configured to output a judgement result when the power supply fault abnormality or the breaking abnormality is judged from one of (i) the selected shift state and the state of the transmission mechanism or (ii) the monitored current value, and
• wherein the control unit is configured to perform a failsafe of the solenoid valve in accordance with the judgment result of the failure judgment device.