DTC P0719: Brake Switch Circuit - Low Input (4L60-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 brake switch indicates brake pedal status to the Powertrain Control Module (PCM). The brake switch is a normally-closed switch that supplies battery voltage on the TCC brake switch signal circuit to the PCM. Applying the brake pedal opens the switch, interrupting voltage to the PCM. When the brake pedal is released, the PCM receives a constant voltage signal. If the PCM receives a zero voltage signal at the brake switch input, and the Torque Converter Clutch (TCC) is engaged, the PCM de-energizes the TCC solenoid valve. When the PCM detects an open brake switch circuit, 0 volts, low input, during accelerations, then DTC P0719 sets.