DTC P0504-00: Brake Switch 'A'/'B' Correlation: General Description
WARNING: This page is about a different car, the 2021 Kia Soul. However, it is still accessible from the selected car via links, so may be relevant.
The brake switch is used to judge whether the acceleration system is abnormal or not. The brake switch has a duplex system (signals brake test or brake light) to memorize the abnormality when the signals of depressing and releasing the brake pedal are detected simultaneously.