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.

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 speed sensors are sent to TERMINAL SPD of the engine control module. via the combination meter. At the same time, the throttle valve opening signal is sent from the throttle body assembly 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 the appropriate current to the electronically controlled transmission solenoid.

2. Stop Light SW Circuit 

   If the brake pedal is depressed (Stop light SW on) while driving in a lockup condition, a signal is sent to TERMINAL STP of the engine control module, the engine control module activates and cuts the current to the solenoid to release the lockup.

3. Overdrive Circuit 

   * Overdrive on

   When the engine is turned from off to on from ignition off, the engine control module turns the O/D on. When the O/D main SW is pushed while the O/D is off, a signal is sent to TERMINAL ODMS of the engine control module, and the O/D is turned on by the engine control module. In this case, the engine control module controls the gear shift according to the vehicle driving conditions, using the O/D range. At this time, the O/D off indicator light will be off.

   * Overdrive off

   When the O/D main SW is pushed while the O/D is on, a signal is sent to TERMINAL ODMS of the engine control module, and the O/D is turned off. At this time, current flows through the O/D off indicator light to TERMINAL ODLP of the engine control module. As a result, the O/D off indicator light turns on, and the engine control module controls the gear shift according to the vehicle driving conditions, without using the O/D range.