Diagnosis - A650E: Description
Automatic transmission is electronically controlled. Transmission shifting and torque converter lock-up are controlled by an Electronic 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 accumulator control valve. Valve assists in smooth shifting. Solenoids are mounted on transmission valve body. See Fig 1.
A pattern select switch is located near selector lever on center console. Pattern select switch contains a POWER (PWR), NORMAL 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 indicator light on instrument panel indicates pattern select switch is in PWR (on) position. When pattern select switch is depressed to SNOW position, rear wheel spin is controlled appropriately.
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. In case of a malfunction, selector lever can be released by depressing shift lock override button, located near selector lever. 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.