P0573: brake messages disagree in the high-direction monitor

P0573 identifies the opposite brake-input disagreement to P0572 in this GM example. The BCM reports initial brake-pedal travel as FALSE while the ECM's discrete electrical switch input is TRUE. The generic high-circuit label alone does not explain this comparison.

Separate the reported states

Inspecting only one brake PID can conceal the issue. The important observation is whether the electrical indication remains true while the BCM initial-travel message reports no travel. A change in either input can remove that disagreement, so the code cannot by itself assign the failure to the switch, BCM, or engine controller.

The source requires BCM communication to be present. It also describes an accumulated sample decision rather than a fault caused by any single disagreement during a transition. Capture the two inputs together when assessing intermittent behavior; a snapshot taken at different times is a weaker comparison.

What cruise behavior tells you

The documented response substitutes TRUE for initial brake travel and disengages cruise until the diagnostic passes. A persistent applied-brake indication after setting may thus be a commanded fallback. It is not independent confirmation that the driver is pressing the pedal.

After the vehicle-specific cause is addressed, verify that both underlying states agree on application and release and that the diagnostic passes. The table classifies this as Type C without an emissions MIL. Absence of that lamp does not validate the brake inputs, and the table provides no basis for judging the vehicle safe to drive.

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 339.