TORQUE CONVERTER LOCK-UP CONTROL FOR AUTOMATIC TRANSMISSION HAVING MANUAL MODE

A torque converter lock-up clutch controlling system for a vehicle drive train inputs a vehicle speed signal and an engine load signal. The vehicle drive train includes an automatic transmission operable in a manual ("M") ratio change mode when an operator selects a "M" range position. The system enables the automatic transmission to behave like a manual transmission upon selection of the "M" range position. A memory includes a "M" range lock-up shift point map for storing data which relates the lock-up application and release to the vehicle speed and engine load signals. The "M" range lock-up shift point map includes lock-up application values, which correspond to the magnitudes of the vehicle speed signal at which lock-up clutch applications are to occur. The magnitudes of the vehicle speed signal at which lock-up clutch applications are to occur are determined in a manner as a function of the magnitudes of the engine load signal. The "M" range lock-up shift point map includes a lock-up release value which corresponds to the magnitude of the vehicle speed signal at which lock-up clutch releases are to occur regardless of the magnitudes of the engine load signal. A controller receiving the vehicle speed and engine load signals, retrieves data from the "M" range lock-up shift point map and processes the retrieved data to produce a lock-up signal. A lock-up actuator controls the toque converter lock-up clutch in response to the lock-up signal.