Washer Level Warning Switch
WARNING: This page is about a different car, the 2002 Lexus GS 430 and 2002 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.
For washer level warning switch component test, see WINDOW WASHER LEVEL WARNING SWITCH under COMPONENT TESTS in INSTRUMENT PANEL article in ACCESSORIES & EQUIPMENT.