from the output of sensor 62 at step 180 engine speed is determined from the output of sensor 60 at step 182 the current magnitude of clutch slip is calculated by subtracting transmission input speed 178 from engine speed 180 at step 184 the engine throttle position is determined from the output of sensor 56 engine output torque is determined at step 186 from engine throttle position 182 and engine speed 180 clutch energy monitor contains a clutch energy function 190 preferably determined empirically by measuring temperature at critical areas of bypass clutch 24 for a range of magnitudes of engine torque and clutch slip the magnitude of energy currently being applied to clutch 24 is determined at step 188 for the current engine torque 186 and current clutch slip 182 and compared the clutch energy defined by function 190 if the magnitude of energy applied to the clutch during the lugging control becomes greater than the acceptable magnitude of energy defined by function 190 control passes either to step 192 where the torque converter 10 is fully open and bypass clutch 24 is fully disengaged or preferably to step 194 where a shift to another gear occurs if the magnitude of energy applied to the clutch during the lugging control is less than the acceptable magnitude of energy defined by function 190 current clutch slip 182 is fed back to step 172 where target clutch slip is updated and any change required to clutch torque capacity to align current clutch slip with the updated clutch slip is determined the control strategy then minimizes clutch slip.