Diagnostic Procedure
WARNING: This page is about a different car, the 2002 Toyota Avalon and 2001 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.
Remove and check operation of the suspect shift solenoid. See SOLENOIDS under COMPONENT TESTS. Replace the faulty shift solenoid as necessary. If the shift solenoid is okay, check and repair the valve body. See appropriate OVERHAUL article. If the valve body is okay, repair internal transaxle malfunction.