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 control signal to TERMINAL THW of the engine control module from the water temp. sensor and the vehicle speed signal is input from the transmission revolution sensor (electronically controlled transmission) to TERMINAL SP2+ 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 a 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. Line Hydraulic Pressure Control 

   The engine control module optimizes the line hydraulic pressure by controlling TERMINAL SLT+ of the module according to the engine torque data. This enhances the smooth gear shifting.

3. High Response Gear Shifting Control 

   In order to control ignition-timing lag, the engine control module is highly responsive in increasing the torque as well as opening the electronic throttle when shifting down in gears. By doing this the gear shifting can be performed in a short period of time. Moreover, the engine control module uses orifice switching control, which optimizes the speed of applying and reducing the hydraulic pressure. And it allows fine shifting capabilities by applying or reducing the hydraulic pressure slowly when it is important to reduce the gear shift shock, and does it quickly when a quick response is required.

4. Clutch Hydraulic Pressure Control 

   The engine control module optimizes the clutch operation and applies the most appropriate hydraulic pressure according to the engine torque data and the number of the clutch revolutions.

5. Lock-Up Control 

   The engine control module carries out lock-up control by adjusting TERMINAL SLU+ of the engine control module according to the shift position, vehicle speed, throttle opening degree and running conditions.

6. Stop Lamp SW Circuit 

   If the brake pedal is depressed (Stop lamp SW on) when driving in a lockup 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 lockup.

7. AI-Shift Control 

   The engine control module determines whether the slope of the road is heading downwards or upwards by monitoring the throttle opening degree or the vehicle's speed. Moreover it can predict winding roads by detecting the turning condition of the vehicle. The engine control module prevents unnecessary shifting above fourth gear and automatically shifts down to the third gear as needed, in order to control the vehicle running according to the road conditions. The engine control module also reads the driver's intention during driving from their acceleration pattern and the running conditions of the vehicle. As a result of that, ideal shifting patterns for different drivers are automatically selected without any manual switching operations.