Low Oil Pressure Warning Switch

WARNING: This page is about a different car, the 2003 Lexus IS 300 and 2002 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.

Disconnect the connector from the switch. See Fig 1.
Check that continuity exists between the terminal and ground with the engine stopped.
Check that no continuity exists between the terminal and ground with the engine running.
Oil pressure should be over 3.55 psi (24.5 kPa). If the operation is not as specified, replace the switch.

Fig 1: Inspecting Low Oil Pressure Switch Continuity