Patent ID: 7107134

Claim:
A default method of operation for a motor vehicle powertrain ( 10 ) including a multi-gear ratio power transmission ( 14 ), transmission output speed measuring apparatus ( 32 c ), transmission input speed measuring apparatus ( 32 b ), and vehicle speed measuring apparatus ( 38 a , 38 b , 36 ), the method comprising the step of: detecting a malfunction ( 86 , 96 , 98 ) of the transmission output speed measuring apparatus ( 32 c ); in response to a detected malfunction of the transmission output speed measuring apparatus ( 32 c ), determining a default transmission output speed value based on an input speed signal ( 128 ) produced by the transmission input speed measuring apparatus ( 32 b ) during a non-shifting mode of operation of said power transmission ( 14 ), and based on a vehicle speed signal ( 130 ) produced by the vehicle speed measuring apparatus ( 38 a , 38 b , 36 ) during a shifting mode of operation of said power transmission ( 14 ); and substituting ( 28 ) said default transmission output speed value for an output speed signal produced by said transmission output speed measuring apparatus ( 32 c ) so long as a malfunction of said transmission output speed measuring apparatus ( 32 c ) is detected.