System Outline

Previous automatic transmissions have selected each gear shift using mechanically controlled throttle hydraulic pressure, governor hydraulic pressure and lockup hydraulic pressure. The electronically controlled transmission, however, electrically controls the line pressure, throttle pressure, lockup pressure and accumulator pressure etc. through solenoid valves. The electronically controlled transmission is a system which precisely controls the gear shift timing and lockup timing in response to the vehicle driving conditions and the engine conditions detected by various sensors. It makes smooth driving possible by selecting the gear which is most appropriate to the driving conditions at that time, and also by preventing downing, squat and gear shift shock when starting off.

1. Gear Shift Operation 

   When driving, the engine warm up condition is input as a signal to TERMINAL THW of the engine control module from the engine coolant temp. sensor and the vehicle speed signal is input to TERMINAL SPD of the engine control module. At the same time, the throttle valve opening signal from the throttle position sensor is input to TERMINALS VTA1 and VTA2 of the engine control module as throttle angle signal.

   Based on these signals, the engine control module selects the best shift position for the driving conditions and sends current to the electronically controlled transmission solenoid.

2. Lock-Up Operation 

   When the engine control module recognizes, from received signals, that the LOCK-UP condition is satisfied, current flows from the engine control module TERMINAL DSL to electronically controlled transmission solenoid TERMINAL 10. At the same time, current flows from the engine control module TERMINAL SL1+ to the electronically controlled transmission solenoid TERMINAL 6 and then out TERMINAL 13 to the engine control module TERMINAL SL1-. This activates the LOCK-UP solenoid to perform the LOCK-UP operation.

3. Stop Light SW Circuit 

   If the brake pedal is depressed (Stop Light SW on) when driving in the lock-up condition, a signal is input to TERMINAL STP of the engine control module. The engine control module operates and cuts the current to the solenoid to release the lock-up.

4. Sequential Shift Operation 

   With the sequential shift function, the manual shift lever becomes available by setting the shift lever to the S position, and the S and range display indicators appear in the combination meter. Any desired range can be selected by shifting the shift lever up or down.