System and method for heating vehicle transmission fluid with a clutch

A method of heating automatic transmission fluid (ATF) in an automatic transmission having a housing containing the ATF, and a plurality of clutches configured to be engaged in various combinations to generate gear ratios corresponding to forward speeds of the automatic transmission, the method comprising:

• moving a friction clutch of the plurality of clutches to an engaged state when the automatic transmission is in a first gear, the friction clutch of the plurality of clutches being movable between a disengaged state, the engaged state where the friction clutch is utilized to generate one or more of the gear ratios of the automatic transmission, and a slippingly engaged state where the friction clutch is commanded to a position of partial engagement between that of the disengaged state and the engaged state such that the friction clutch is not engaged to generate gear ratios of the automatic transmission in the slippingly engaged state;
• moving the friction clutch to the slippingly engaged state to generate heat from friction when the friction clutch is not being utilized to generate one or more of the gear ratios;
• and
• heating the ATF in the housing from the heat generated by the friction clutch being in the slippingly engaged state to improve operating efficiency of the automatic transmission.