Description & Operation
The A-650E transmission is a 5-speed Electronic Controlled Transmission (ECT). A new gear ratio has been added between 1st and 2nd gear. This gear is used by activating overdrive circuit while vehicle is in 1st gear. Solenoids that control shifts are located in valve body. Transmission consists of lock-up type torque converter, OD direct clutch, direct clutch, forward clutch, 3rd brake, 3rd coast brake, 2nd brake, OD brake, 3 one-way clutches, 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 LEXUS A-650E ELECTRONIC CONTROLS article. ECT ECU receives signals from various input devices and uses these signals 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 "4" position, engine braking occurs and transmission downshifts to "4" gear. Shifting into overdrive is not possible. Transmission will select appropriate gear for current conditions such as hill climbing, hard towing, etc.
A pattern select switch is located near selector lever on center console. Pattern select switch contains a POWER (PWR), NORMAL (ECT) and SNOW operating positions. When pattern select switch is depressed to 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. When pattern select switch is depressed to SNOW position, transmission starts out in 2nd gear.
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 SYSTEM article.