P25A2: A brake-module MIL request points to another controller’s evidence

P25A2 records that the brake system control module has requested malfunction-indicator illumination because it detected an emissions-related fault. The receiving monitor is supervising that request message. It is not independently measuring brake pressure, wheel speed or mechanical brake performance.

Find the fault behind the request

The defining condition combines an emissions-related DTC in the brake controller with that module requesting the MIL. Consequently, the originating controller’s own fault record is the meaningful next source of diagnostic detail. P25A2 by itself does not identify the underlying brake-system component.

The monitor becomes eligible after more than three seconds since power-up and operates continuously. An observation during the initial power-up interval should not be treated as equivalent to an established request detected after that delay.

Separate message reporting from lamp behavior

The table’s reporting column includes “No MIL” for this receiving monitor. That must not be turned into a guarantee that the lamp is off: the condition being recorded is another module’s illumination request. The summary alone does not explain every interaction governing the final lamp state.

Preserve the requesting-module identity, its DTCs and their status alongside the receiving code. Clearing one record without understanding the originating request can remove context while leaving the initiating problem unresolved. Because a brake controller is involved, a code string alone cannot establish whether braking is safe or authorize component replacement.

Source and applicability

2025 GM 25OBDG04A documented monitor only. Vehicle, engine and calibration applicability must be confirmed from the matching service information; no model fitment is inferred. These criteria explain controller logic, not a complete repair procedure. 25OBDG04A, PDF page 657.