Inspection Procedure 3: Brake warning light stays ON with the parking brake lever released (ABS warning light is OFF): Operation

WARNING: This page is about a different car, the 2014 Mitsubishi Outlander. However, it is still accessible from the selected car via links, so may be relevant.

When the parking brake switch is turned ON, the combination meter (BRK terminal) is grounded, and the brake warning light illuminates.
When reduction of the brake fluid amount is detected, the brake fluid level switch is turned from ON to OFF. ETACS-ECU monitors the brake fluid level switch, and instructs the combination meter via the CAN bus line to illuminate the brake warning light.