Supra Liftback L6-2997cc 3.0L DOHC MFI Twin-Turbo (1997)
electronically controlled transmission is a system which precisely controls gear shift timing and lock-up timing in response to the vehicle's driving
conditions and the engine operating conditions detected by various sensors, making smooth driving possible by shift selection for each gear which is the
most appropriate to the driving conditions at that time, and controls the engine torque during shifting to achieve optimum shift feeling.
1. GEAR SHIFT OPERATION
When driving, the engine warm up condition is input as a signal to TERMINAL B-44 of the engine control module from the engine coolant temp.
sensor and the vehicle speed signal from vehicle speed sensor no.2 is input to TERMINAL B-23 of the engine control module. At the same time,
the throttle valve opening signal from the throttle position sensor (main) is input to TERMINAL B-43 of the engine control module as throttle
angle signal.
Based on these signals, the engine control module selects the best shift position for driving conditions and sends current to the electronically
controlled transmission solenoids.
When shifting to 1st speed, the current flows from TERMINAL B-10 of the engine control module --> TERMINAL 4 of electronically
controlled transmission solenoid --> GROUND and continuity to no.1 solenoid causes the shift (no.2 solenoid does not have continuity at this
time).
For 2nd speed, the current flows simultaneously from TERMINAL B-9 of the engine control module --> TERMINAL 8 of electronically
controlled transmission solenoid --> GROUND, and from TERMINAL B-10 of the engine control module --> TERMINAL 4 of electronically
controlled transmission solenoid --> GROUND, and continuity to no. and no.2 solenoids causes the shift.
For 3rd speed, there is no continuity to no.1 solenoid, only to no.2 solenoid, causing the shift.
Shifting into the 4th speed (overdrive) occurs when no current flows to no.1 and no.2 solenoids. The no.4 solenoid (for accumulator back pressure
modulation) is installed to adjust the back pressure on the accumulator and controls the hydraulic pressure during shifting and lock-up in order to
provide smooth shifting with little shift shock.
2. LOCK-UP OPERATION
When the engine control module decides, based ON each signal, that the lock-up condition has been met, the current through EFI No.1 fuse flows
from the EFI main relay --> TERMINAL 3 of electronically controlled transmission solenoid --> TERMINAL 7 --> TERMINAL B-14 of the
engine control module --> GROUND, so continuity to no.3 (for lock-up) causes lock-up.
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 A-4 of the engine control
module. The engine control module operates and cuts the current to the solenoid to release lock-up.
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 A-28 of the engine control module and the
electronically controlled transmission causes shift to overdrive 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 flowing through the O/D OFF indicator light flows to GROUND by
way of the O/D main SW and causes the O/D OFF indicator light to light up. At the same time, a signal is input to TERMINAL A-28 of the
engine control module and the electronically controlled transmission prevents shift into overdrive.
5. ELECTRONICALLY CONTROLLED TRANSMISSION PATTERN SELECT SW CIRCUIT
When the electronically controlled transmission pattern select SW is switched from normal to manual, a signal is input to TERMINAL A-18 of
the engine control module. Input of this signal causes current to flow from the GAUGE fuse to TERMINAL A-1 of the combination meter -->
TERMINAL A-12 --> TERMINAL A-25 of engine control module --> GROUND, lighting up the indicator light. If the A/T shift lever is then
shifted to "2" position, the engine control module enables the vehicle to start off with the transmission in 2nd gear. Thus permitting easing starting
off and driving on slippery roads.
6. CRUISE CONTROL
When cruise control operation is selected a signal is input to TERMINAL A-12 of the engine control module from cruise control ECU. As a
result, the engine control module operates and controls overdrive, lock-up and so on for smooth driving.
