Brake Fluid Level Warning Switch

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