Importance

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Abstract

An automatic transmission includes a planetary gear mechanism, an engagement element group including a particular engagement element having first and second pressure chambers, a pressure control valve to regulate the fluid pressure for the particular engagement element, and a selector valve arranged to connect the second pressure chamber with the pressure control valve at a first valve position, and to disconnect the second pressure chamber from the pressure control valve at a second valve position. A shift control section is configured to command a shift operation from a first gear position, to a second gear position, by controlling the selector valve to the second valve position and to supply the fluid pressure to the first pressure chamber, and to judge the selector valve to be in an abnormal state, in accordance with a parameter in the shift operation.

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First Claim