"When TCC (Torque Converter Clutch) is commanded on (at or near 100% duty cycle) TC_SLIPACT should be near 0 RPM, indicating that TCC is fully locked. TC_SLIPACT indicates the actual amount of slippage within the torque converter. TC_SLIPACT is a value calculated by the PCM, and is the difference in RPM between the engine crankshaft and the transmission input shaft."