Shift Indicator - A/T: Description and Operation

The previous automatic transmission has selected each gear shift using mechanically controlled throttle hydraulic pressure, governor hydraulic pressure and lock-up hydraulic pressure. The Electronically Controlled Transmission, however, electrically controls the governor pressure and lock-up pressure through the solenoid valve. The engine control module 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 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 the input signals to TERMINAL SP2+ of the Engine Control Module from the Vehicle Speed Sensor devoted to the Electronically Controlled Transmission. The current is then output to the Electronically Controlled Transmission Solenoids. When shifting to the 1st speed, the current flows from TERMINAL S1 of the Engine Control Module to TERMINAL 1 of the Electronically Controlled Transmission solenoid --> Ground, and continuity to the No.1 solenoid causes the shift. For the 2nd speed, the current flows from TERMINAL S1 of the Engine Control Module to TERMINAL 1 of the Electronically Controlled Transmission solenoid --> Ground, and from TERMINAL S2 of the Engine Control Module to TERMINAL 2 of the Electronically Controlled Transmission solenoid --> Ground, and continuity to No.1 and No.2 solenoids causes the shift. For the 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, the current flows from TERMINAL SL of the Engine Control Module to TERMINAL 3 of the Electronically Controlled Transmission 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 STP 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), the current from 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 the Engine Control Module operation prevents shift into overdrive.

5. ELECTRONICALLY CONTROLLED TRANSMISSION PATTERN SELECT 5W CIRCUIT
If the Electronically Controlled Transmission pattern select SW is changed from normal to power, the current through the power indicator flows to GROUND, and flows to TERMINAL PWR of the engine control module, the engine control module operates, and shift up and shift down occur at higher vehicle speeds than when the SW is in 2nd position.

6. TRANSFER SHIFT OPERATION
When the Transfer Shift Lever is moved to L4 position, a signal from transfer L4 position SW is input to the TERMINAL L4 of the engine control module, then shift to L4 occurs.