Door Courtesy Switch
WARNING: This page is about a different car, the 2002 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.
Turn ignition off. Remove door courtesy switch from door pillar post and disconnect electrical harness connector. Using an ohmmeter, check that continuity exists between door courtesy switch terminal and switch body with switch pin released (ON position) and no continuity exists with switch pin depressed (OFF position). See Fig 1. Replace door courtesy switch if continuity is not as specified.