System Outline

Previous automatic transmissions have selected each gear shift using mechanically controlled throttle hydraulic pressure, governor hydraulic pressure, and lock-up hydraulic pressure. The Electronically Controlled Transmission (ECT), however, electrically controls the line pressure, and lock-up pressure etc., through solenoid valves. The Engine Control Module (ECM) controls of the solenoid valves based on the input signals from various sensors, and in this way makes the shift selection for each gear which is the most appropriate to the driving conditions at that time.

1. GEAR SHIFT OPERATION
During driving, the ECM 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 ECM, and also the input signals to TERMINAL NC2+ of the ECM from the vehicle speed sensor devoted to the Electronically Controlled Transmission. Current is then output to the Electronically Controlled Transmission Solenoid. When shifting to 1st speed, current flows from TERMINAL S1 of the ECM --> TERMINAL 3 of the Electronically Controlled Transmission Solenoid --> GROUND, and continuity to the No.1 Solenoid causes the shift.
For 2nd speed, the current flows from TERMINAL S1 of the ECM --> TERMINAL 3 of the Electronically Controlled Transmission Solenoid --> GROUND, and from TERMINAL S2 of the ECM --> TERMINAL 6 of the Electronically Controlled Transmission Solenoid --> 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.

2. LOCK-UP OPERATION
When the ECM judges from each signal that lock-up operation conditions have been met, current flows from --> TERMINAL SL of the ECM --> TERMINAL 2 of Electronically Controlled Transmission solenoid --> GROUND, causing continuity to 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 into TERMINAL STP of the ECM, the ECM operates and continuity to the Lock-Up Solenoid is cut.

4. OVERDRIVE CIRCUIT
* Overdrive Switch ON
When the O/D Main SW is turned ON (O/D OFF Indicator Light turns OFF), a signal is input into TERMINAL OD2 of the ECM and the ECM operation causes gear shift when the conditions for overdrive are met.

* Overdrive Switch OFF
When the O/D Main SW is turned to OFF, (O/D OFF Indicator Light turns ON) 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 ECM and ECM operation prevents shift into overdrive.

5. ELECTRONIC CONTROLLED TRANSMISSION PATTERN SELECT SW CIRCUIT
If the Electronically Controlled Transmission pattern select SW is changed from "Normal" to "Power", the current through the Mode Indicator Light flows to GROUND, current flows to TERMINAL P of ECM, the ECM operates, and shift up and shift down occur at a higher vehicle speeds than when the SW is in "NORMAL" position.