Description & Operation
A-340 series automatic transmission is a 4-speed electronic controlled transmission. Solenoids that control shifts are located in valve body. Transmission consists of lock-up type torque converter, OD direct clutch, direct clutch, forward clutch, 2nd brake, 2nd coast brake, OD brake, overdrive planetary gear unit, planetary gear unit, hydraulic control system and electronic control system. See Fig 1.
Solenoids are controlled by an Electronic Controlled Transmission (ECT) Electronic Control Unit (ECU). Control unit is referred to as ECT ECU. For electronic diagnosis, see TOYOTA A-340 SERIES ELECTRONIC CONTROLS article. ECT ECU receives information from various input devices and uses this information to control solenoids for transmission shifting and lock-up solenoid for torque converter lock-up.
When selector lever is shifted into "D" position, transmission will perform normal shift pattern including overdrive. When selector lever is shifted into "3" position, transmission will perform 1st, 2nd and 3rd gear shifts, but will not shift into overdrive.
A pattern select switch is located near selector lever on center console. Pattern select switch contains a POWER (PWR), SNOW and a NORMAL (ECT) operating position. When pattern select switch is depressed (PWR position), transmission upshifts and downshifts will occur at a higher vehicle speed than with switch released. An ECT PWR indicator light on instrument panel indicates pattern select switch is in PWR (on) position.
Transmission is equipped with a shift lock and key lock system. Shift lock system prevents selector lever from being moved from Park unless brake pedal is depressed. Key lock system prevents ignition key from being moved from ACC to LOCK position on ignition switch unless selector lever is in Park. For more information on shift lock and key lock system, see TOYOTA & LEXUS SHIFT LOCK SYSTEMS article.