Description & Operation: Introduction
Automatic transmission is electronically controlled. Transmission shifting and torque converter lock-up are controlled by an Engine Control Module (ECM). ECM receives information from various input devices and uses this information to control shift solenoids for transmission shifting and lock-up solenoid (also called SLU solenoid) for torque converter lock-up. SLN solenoid is used to control hydraulic pressure acting on the accumulator control valve. This valve assists in smooth shifting. The solenoids are mounted on transmission valve body. See Fig 1.
A pattern select switch is located near the gearshift lever on the center console. The pattern select switch contains 3 operating positions, POWER (PWR), NORMAL and SNOW. When the pattern select switch is depressed to the PWR position, transmission upshifts and downshifts will occur at a higher vehicle speed than with switch released. An indicator light on instrument panel indicates pattern select switch is in PWR (on) position. When the pattern select switch is depressed to SNOW position, rear wheel spin is controlled appropriately.
Transmission is equipped with a shift interlock and key lock system. The shift interlock system prevents the gearshift lever from being moved from Park unless the brake pedal is depressed. In case of a malfunction, the gearshift lever can be released by depressing the shift lock override button, located near the gearshift lever. The key lock system prevents the ignition key from being moved from ACC to LOCK position on the ignition switch unless the gearshift lever is in Park. For more information on shift interlock and the ignition key lock system, see SHIFT INTERLOCK SYSTEMS - LEXUS & TOYOTA article.