DTC P0724: Brake Switch Circuit - High Input (4L80-E Transmission): Description
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, 2002 Chevrolet RV Cutaway, and 2002 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
The TCC Brake switch indicates the brake pedal status. The normally closed brake switch supplies a battery voltage signal to the Powertrain Control Module (PCM). The signal voltage circuit opens when the brakes are applied. If the PCM detects a closed TCC Brake switch during decelerations, then DTC P0724 sets.