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TM-26 < FUNCTION DIAGNOSIS > A/T CONTROL SYSTEM When shifting from the lock-up released state to the lock-up applied state, the current output to the torque con- verter clutch solenoid is controlled with the TCM. In this way, when shifting to the lock-up applied state, the torque converter clutch is temporarily set to the half-clutched state to reduce the shock. Half-clutched State • The current output from the TCM to the torque converter clutch solenoid is varied to gradually increase the torque converter clutch solenoid pressure. In this way, the lock-up apply pressure gradually rises and while the torque converter clutch piston is put into half-clutched status, the torque converter clutch piston operating pressure is increased and the coupling is completed smoothly. Slip Lock-up Control • In the slip region, the torque converter clutch solenoid current is controlled with the TCM to put it into the half-clutched state. This absorbs the engine torque fluctuation and lock-up operates from low speed. This raises the fuel efficiency for 4GR and 5GR at both low speed and when the accelerator has a low degree of opening. Engine Brake Control INFOID:0000000005148516 • The forward one-way clutch transmits the drive force from the engine to the rear wheels. But the reverse drive from the rear wheels is not transmitted to the engine because the one-way clutch is idling. Therefore, the low coast brake solenoid is operated to prevent the forward one-way clutch from idling and the engine brake is operated in the same manner as conventionally. • The operation of the low coast brake solenoid switches the low coast brake switching valve and controls the coupling and releasing of the low coast brake. The low coast brake reducing valve controls the low coast brake coupling force. Control Valve INFOID:0000000005148517 FUNCTION OF CONTROL VALVE SCIA1520E Name Function Torque converter regulator valve In order to prevent the pressure supplied to the torque converter from being excessive, Pressure regulator valve Adjusts the oil discharged from the oil pump to the optimum pressure (line pressure) for Front brake control valve When the front brake is coupled, adjusts the line pressure to the optimum pressure (front Accumulator control valve Adjusts the pressure (accumulator control pressure) acting on the accumulator piston |