Step 10 - Inspect Brake Fluid Level Warning Switch Continuity

WARNING: This page is about a different car, the 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.

Remove the reservoir tank cap and strainer.
Disconnect the connector.
Check that no continuity exists between terminals with the switch OFF (float up).

Fig 1: Testing Brake Fluid Level Warning Switch
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Use siphon, etc. to take fluid out of the reservoir tank.
Check that continuity exists between terminals with the switch ON (float down).
Pour the fluid back in the reservoir tank.

If operation is not as specified, replace the switch.