Theory Of Operation

When in 2nd, 3rd, or 4th gear, the Torque Converter Clutch (TCC) can be locked or partially locked when certain conditions are met. The TCC piston is electronically modulated by increasing the duty cycle of the LR/TCC solenoid until the torque converter slip difference (difference between engine and turbine speed) is within 60 RPM. Then the LR/TCC solenoid is fully energized (FEMCC / 100% duty cycle). Torque converter slip is monitored in FEMCC to ensure adequate clutch capacity. The MIL will illuminate if the trans accumulates five minutes of inadequate TCC capacity (slip) while in FEMCC mode. The transmission will still attempt normal EMCC operation (will not be in Limp-in) even after the MIL is illuminated.