Transmission Control Systems: Description and Operation

The electronically controlled transmission electrically controls the, throttle pressure, lock-up pressure, and accumulator pressure etc. through the solenoid valve.
The electronically controlled transmission is a system which precisely controls the gear shift timing and lock-up timing in response to the vehicle's driving conditions and the engine condition detected by various sensors. It makes smooth driving possible by shift selection of the gear which is the 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 input as a control signal from the engine coolant temp. sensor to TERMINAL THW of the engine control module, and the vehicle speed is input to TERMINAL SP2+ of the engine control module from the vehicle speed sensor. At the same time, the throttle valve opening signal from the throttle position sensor is input to TERMINALS VTA, 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. LOCK-UP OPERATION
When the engine control module decides based on each signal that the lock-up condition has been met, the current flows from the engine control module TERMINAL SL to TERMINAL 7 of the electronically controlled transmission solenoid to GROUND.

3. STOP LIGHT SW CIRCUIT
If the brake pedal is depressed (Stop light SW on) when driving in lock-up position, a signal is input to TERMINAL STP of the engine control module. As a result, the engine control module cuts the current to the solenoid to release the lock-up.

4. OVERDRIVE CIRCUIT
* O/D main SW on
When the O/D main SW is switched to ON position, a signal is input to TERMINAL 0D2 of the engine control module, and enables shift change to the overdrive range, through the control of the engine control module.
* O/D main SW off
When the O/D main SW is switched to OFF position, a signal is input to TERMINAL 0D2 of the engine control module, and prohibits shift change to the overdrive range through the control of the engine control module. When in the overdrive range already, shift down is made.