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ECT AND A/T INDICATOR (3S–FE)
PREVIOUS AUTOMATIC TRANSMISSIONS HAVE SELECTED EACH GEAR SHIFT USING MECHANICALLY CONTROLLED THROTTLE
HYDRAULIC PRESSURE, GOVERNOR HYDRAULIC PRESSURE AND LOCK–UP HYDRAULIC PRESSURE. THE ECT, HOWEVER,
ELECTRICALLY CONTROLS THE LINE PRESSURE AND LOCK–UP PRESSURE ETC., THROUGH THE SOLENOID VALVE. ECT
COMPUTER CONTROL OF THE SOLENOID VALVE BASED ON THE INPUT SIGNALS FROM EACH SENSOR MAKES SMOOTH DRIVING
POSSIBLE BY SHIFT SELECTION FOR EACH GEAR WHICH IS MOST APPROPRIATE TO THE DRIVING CONDITIONS AT THAT TIME.
1. GEAR SHIFT OPERATION
DURING DRIVING, THE COMPUTER SELECTS THE SHIFT FOR EACH GEAR WHICH IS MOST APPROPRIATE TO THE DRIVING
CONDITIONS, BASED ON INPUT SIGNALS FROM THE TCCS ECU TO TERMINALS IDL, L1, L2 AND L3 OF THE ECT COMPUTER, AND
ALSO THE INPUT SIGNALS TO TERMINAL SP2 (FWD), OF THE COMPUTER FROM THE SPEED SENSOR. CURRENT IS THEN OUTPUT
TO THE ECT SOLENOIDS. WHEN SHIFTING TO 1ST SPEED, CURRENT FLOWS FROM TERMINAL S1 OF THE COMPUTER → TERMINAL
3 (FWD), 2 (4WD) OF THE ECT SOLENOIDS → GROUND, AND CONTINUITY TO THE NO. 1 SOLENOID CAUSES THE SHIFT.
FOR 2ND SPEED, CURRENT FLOWS FROM TERMINAL S1 OF THE COMPUTER → TERMINAL 3 (FWD), 2 (4WD) OF THE ECT
SOLENOIDS → GROUND, AND FROM TERMINAL S2 OF THE COMPUTER → TERMINAL 2 (FWD), 1 (4WD) OF THE ECT SOLENOIDS →
GROUND, AND CONTINUITY TO SOLENOIDS NO. 1 AND NO. 2 CAUSES THE SHIFT.
FOR 3RD SPEED, THERE IS NO CONTINUITY TO NO. 1 SOLENOID, ONLY TO NO. 2, CAUSING THE SHIFT. SHIFTING INTO 4TH SPEED
(OVERDRIVE) TAKES PLACE WHEN THERE IS NO CONTINUITY TO EITHER NO. 1 OR NO. 2 SOLENOID.
2. LOCK–UP OPERATION
WHEN THE ECT COMPUTER JUDGES FROM EACH SIGNAL THAT LOCK–UP OPERATION CONDITIONS HAVE BEEN MET, CURRENT
FLOWS FROM TERMINAL SL OF THE ECT COMPUTER → TERMINAL 1 (FWD), 3 (4WD) OF THE ECT SOLENOID → GROUND, CAUSING
CONTINUITY TO THE LOCK–UP SOLENOID AND CAUSING LOCK–UP OPERATION.
3. STOP LIGHT SW CIRCUIT
IF THE BRAKE PEDAL IS DEPRESSED (STOP LIGHT SW ON) WHEN DRIVING IN LOCK–UP CONDITION, A SIGNAL IS INPUT TO
TERMINAL BK OF THE COMPUTER, THE COMPUTER OPERATES AND CONTINUITY TO THE LOCK–UP SOLENOID IS CUT.
4. OVERDRIVE CIRCUIT
* O/D MAIN SW ON
WHEN THE O/D MAIN SW IS TURNED ON (O/D OFF INDICATOR LIGHT TURNS OFF), A SIGNAL IS INPUT TO TERMINAL OD2 OF THE
COMPUTER AND COMPUTER OPERATION CAUSES GEAR SHIFT WHEN THE CONDITIONS FOR OVERDRIVE ARE MET.
* O/D MAIN SW OFF
WHEN THE OVERDRIVE SW IS TURNED TO OFF, THE CURRENT FLOWING THROUGH THE O/D OFF INDICATOR LIGHT FLOWS
THROUGH THE O/D MAIN SW TO GROUND, CAUSING THE INDICATOR LIGHT TO LIGHT UP. AT THE SAME TIME, A SIGNAL IS INPUT
TO TERMINAL OD2 OF THE COMPUTER AND COMPUTER OPERATION PREVENTS SHIFT INTO OVERDRIVE.
5. ECT PATTERN SELECT SW CIRCUIT
IF THE ECT PATTERN SELECT SW IS CHANGED FROM NORMAL TO POWER, THE CURRENT FLOWING THROUGH THE POWER
INDICATOR FLOWS TO GROUND, CURRENT FLOWS TO TERMINAL PWR OF THE ECT COMPUTER, THE COMPUTER OPERATES, AND
SHIFT UP AND SHIFT DOWN OCCUR AT HIGHER VEHICLE SPEEDS THAN WHEN THE SW IS IN NORMAL POSITION.
SYSTEM OUTLINE