Transmission Control Systems: Description and Operation

This system electronically controls the gear shift timing, lock-up timing, the clutch and brake hydraulic pressure, and the engine torque during shifting to achieve optimum shift feeling.
In according to the vehicle driving conditions and engine operating conditions as detected by various sensors.

1. GEAR SHIFT OPERATION
During driving, the engine control module selects the shift for each gear which is most appropriate to the driving conditions. based on input signals from the engine coolant temp. sensor to TERMINAL THW of the engine control module, and also [he input signals to TERMINAL SPD of the engine control module from the vehicle speed sensor devoted to the electronically controlled transmission. Current is then output to the electronically controlled transmission solenoids. When shifting to 1ST speed, current flows from TERMINAL S1 of the engine control module to TERMINAL 3 of the electronically controlled transmission solenoid to GROUND, and continuity to the No.1 solenoid causes the shift.
For 2ND speed, current flows from TERMINAL S1 of the engine control module to TERMINAL 3 of the electronically controlled transmission solenoid to GROUND, and from TERMINAL S2 of the engine control module to TERMINAL 1 of the electronically controlled transmission solenoid to 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 engine control module judges from each signal that lock-up operation conditions have been met, current flows from TERMINAL SL of the engine control module to TERMINAL 1 of the electronically controlled transmission solenoids to 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 B/K of the engine control module, and the engine control module 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 (SW point is open), a signal is input to TERMINAL OD2 of the engine control module, and engine control module operation causes gear shift when the conditions for overdrive are met.
* O/D main SW OFF
When the O/D main SW is turned OFF (SW point is closed), current 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 engine control module and engine control module operation prevents shift into overdrive.