Brake Lamp Switch
WARNING: This page is about a different car, the 2021 Hyundai Kona. However, it is still accessible from the selected car via links, so may be relevant.
The ESP receives information on connection state of components and operation state through brake circuit. When you hit the brake pedal, the brake circuit sends a "ON" state signal to ESP and the pressure sensor data curve rises. While you release the brake pedal, brake circuit sends an "OFF" state signal to ESP.