Patent ID: 8560190
Filing Date: 2013-10-15
Classification: B60Y,F16H

Abstract:
1. A control device for an automatic transmission that is disposed in a power transfer path from a drive source of a vehicle to drive wheels, that includes a plurality of frictional engagement elements, an input shaft, and an output shaft, and that can establish a plurality of predetermined shift speeds that are different in speed ratio in accordance with an engagement state of the plurality of frictional engagement elements, the speed ratio being a ratio between a rotating speed of the input shaft and a rotating speed of the output shaft, the control device comprising: a neutral control unit that executes neutral control for bringing the automatic transmission into a neutral state by reducing an engagement force for an engaged frictional engagement element in the case where running conditions are satisfied, the neutral state being a state in which power transfer between the input shaft and the output shaft is suppressed, and the running conditions including an accelerator of the vehicle not being operated in a state in which the vehicle is running forward and in a state in which any one of the plurality of predetermined shift speeds is established; a speed ratio specifying unit that specifies an actual speed ratio of the automatic transmission on the basis of the rotating speed of the input shaft and the rotating speed of the output shaft; and a first failure determination unit that determines whether or not a failure is occurring in the automatic transmission on the basis of the actual speed ratio during execution of the neutral control, wherein the first failure determination unit determines that a failure is occurring in the automatic transmission during the neutral state when the actual speed ratio coincides with the speed ratio of any one of the plurality of predetermined shift speeds over a predetermined time.