P0572: brake messages disagree in the low-direction monitor

P0572 is described generically as brake-switch circuit low. In the cited GM implementation it is specifically a disagreement: the BCM serial message indicates initial brake-pedal travel is TRUE while the separate electrical input at the ECM indicates FALSE.

Why the two inputs matter

The code does not establish that the pedal is physically released, or that every brake-related input is low. It establishes that two representations of the same initial movement conflict in a particular direction. A useful diagnostic record therefore includes both the BCM-reported initial-travel state and the discrete ECM switch state during pedal operation.

The monitor requires communication with the BCM to remain available. A missing BCM message is not the condition described by this row; communication faults need their own interpretation before treating an unavailable scan value as a switch disagreement. The table uses a sampled decision, so a brief transition between states is not automatically a confirmed failure.

Consequence and verification

GM specifies that the fallback initial-travel state becomes TRUE and cruise disengages until the diagnostic passes. Seeing a true brake status after the fault may therefore reflect fallback logic rather than physical pedal movement. Verification should establish agreement between the actual inputs through pedal application and release, with the monitor enabled. Brake-input diagnosis should follow the vehicle-specific service procedure; this emissions-monitor summary does not establish brake-system safety or authorize bypassing a brake input.

Source and applicability

Documented monitors in gm-2025-03a, model year 2025. These are module/calibration examples; vehicle, engine and transmission applicability must be confirmed independently. GM 2025-03a, page 338.