Patent ID: 8224542

Claim:
An automatic transmission which has a planetary gear and a plurality of friction elements, and in which a directed gear position is achieved by switching an engagement/release state of the plurality of friction elements, and the directed gear position is one of a plurality of gear positions, the transmission comprising: a controller functioning to: detect repeatedly whether or not a release failure or an engagement failure has occurred in the friction elements while a vehicle is traveling, a release failure occurring when one of the friction elements cannot be engaged even when an engagement command is output thereto and an engagement failure occurring when one of the friction elements cannot be released even when a release command is output thereto; begin failed element specification control to specify the failed one of the friction elements as a specified friction element when a vehicle speed falls to or below a predetermined value for the first time after a failure has been detected, and perform a limp home control which determines usable gear positions on the basis of the specified friction element when the failed one of the friction elements has been specified, and performs a shift control using only the usable gear positions.