Patent ID: 7803081

Claim:
A system for controlling an automatic transmission, the automatic transmission comprising a plurality of friction elements which come into engagement upon being supplied with a working oil and include a lowest gear-stage friction element, the automatic transmission having a lowest gear stage that has a largest gear ratio and a gear stage other than the lowest gear stage, the lowest gear stage being established through engagement of the lowest gear-stage friction element, the gear stage other than the lowest gear stage being established while the lowest gear-stage friction element is kept in disengagement, the system comprising: a sensor that senses a temperature of the working oil in the automatic transmission; and an electronic control unit operative depending on the sensed temperature, the electronic control unit being programmed to: inhibit use of the lowest gear stage and allow use of the gear stage other than the lowest gear stage when the sensed temperature of the working oil is lower than a first predetermined temperature as a predetermined extremely low temperature at which an engagement failure of the lowest gear-stage friction element is caused.