Washer Fluid Level Warning Switch Circuit: Description
WARNING: This page is about a different car, the 2008 Lexus IS F. However, it is still accessible from the selected car via links, so may be relevant.
The front controller receives washer fluid level warning switch condition (on or off) information, and sends it through multiplex communication lines to the combination meter.
The combination meter receives this information, and turns on the washer fluid level warning light when the washer fluid level becomes low.