Check Brake Fluid
WARNING: This page is about a different car, the 2009 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
The IPC illuminates the CHECK BRAKE FLUID indicator in the driver information center (DIC) and sends a serial data message in order to activate an audible warning when the IPC detects that the brake fluid level is below the normal operating range.