P24F1: Wake-up circuit remains high with the command off

P24F1 identifies a control-module wake-up circuit high condition. The 2018 GM monitor evaluates the output with the command off, making the command-feedback relationship more useful than the voltage number alone.

The documented evaluation

A control voltage at or above 13.21 V meets the listed high criterion while the diagnostic is enabled. The controller requires 480 failures among 560 samples, spaced 12.5 milliseconds apart. The row lists a seven-second evaluation and Type A, one-trip reporting.

These values belong to the wake-up output in this GM implementation. They are not a universal battery-voltage limit, and P24F1 should not be turned into a charging-system overvoltage diagnosis merely because a value exceeds 13 V.

Verify the state that failed

A technician should retain the off command and output feedback and use the correct schematic to identify the controlled wake-up path. The code does not identify a particular module that needs replacement. Associated communication or sleep-state observations may help the vehicle-specific investigation, but they do not replace this circuit evidence.

After repair, confirm appropriate behavior with the output commanded off as well as the prescribed wake-up sequence. Successful communication while all modules are awake is not sufficient proof that the output deactivates correctly. Do not manually bridge or energize wake-up wiring from this description; it provides neither a pin-level procedure nor the vehicle's power-management design.

Source and applicability

This explanation follows the documented GM monitor, not a verified application to every vehicle with this code. Confirm the vehicle, reporting module and calibration in current service information. GM diagnostic table, physical page 1261.