System and method of controlling a torque converter lockup clutch

A method for controlling a torque converter lockup clutch for eliminating or reducing shift clutch slip in an automatic transmission, the method comprising the steps of:

• determining if at least one shift clutch of the automatic transmission is slipping and outputting a corresponding slip value;
• disengaging the torque converter lockup clutch if the lockup clutch is in an engaged state and the slip value exceeds a permitted shift clutch slip threshold;
• increasing a differential speed between an input portion and an output portion of the torque converter;
• and
• generating a boost in hydraulic shift clutch pressure, via the increase in differential speed within the torque converter, for reducing slip in the at least one shift clutch.

A torque converter lockup clutch system for an associated automatic transmission, comprising:

• a torque converter including an impeller operatively coupled to an associated internal combustion engine, a turbine operatively coupled to an input shaft of the associated automatic transmission, and a stator disposed in a working fluid pathway between the impeller and the turbine;
• a lockup clutch disposed within the torque converter for selectively locking the impeller to the turbine, the lockup clutch having an engaged state and a disengaged state;
• a reaction arm attached to the stator of the torque converter for transmitting a reaction torque developed by the working fluid of the torque converter;
• a pressure regulator operatively coupled to the reaction arm for adjusting the pressure of the working fluid to an at least one shift clutch of the associated automatic transmission;
• a shift clutch slip detector for detecting a slip condition of the at least one shift clutch, the slip detector outputting a slip signal;
• and
• an engine control unit (ECU) receiving the slip signal and prohibiting the lockup clutch from entering into the engaged state, when the slip signal exceeds a predetermined shift clutch slip threshold.