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, controls the line pressure, throttle pressure, lockup pressure and accumulator pressure etc. electrically via the solenoid valve. The electronically controlled transmission is a system which precisely controls 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 by preventing downing, squat and gear shift shock when starting off.

1. Gear Shift Operation 

   When driving, the engine warm up condition is sent as a signal to TERMINAL THW of the engine control module from the engine coolant temp. sensor, and the vehicle speed signals from the speed sensors are sent to the skid control ECU with actuator, and are sent to the engine control module through communication control. At the same time, the throttle valve opening signal is sent from the throttle position sensor to the TERMINALS VTA1 and VTA2 of the engine control module, as the throttle angle signal.

2. Lock-Up Operation 

   If the engine control module decides, based on the received signals, that the lock-up condition has been met, the current flows through TERMINAL DSL of the engine control module to TERMINAL 3 of the electronically controlled transmission solenoid to GROUND.

3. Stop Light Switch Circuit 

   If the brake pedal is depressed (Stop light switch on) while driving in 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.