P257E: Hood-switch signal is below the configured lower limit

P257E diagnoses a low-voltage or ground-short signature in the hood-switch input in the reviewed GM table. It is an electrical-range fault and should not be interpreted as an ordinary indication that the hood is closed.

The switch configuration controls the threshold

The selected Global A switch uses a lower boundary of 17.2%. The same row lists an alternative Global B boundary of 28.54%. These values describe the reported switch signal; they do not measure hood angle or latch movement.

Confirming switch type is therefore a substantive diagnostic step. A percentage below one version's threshold might be evaluated differently under another version, and the summary does not establish which physical wiring arrangement belongs to an individual vehicle.

Conditions and persistence

For the documented configuration, run/crank is used as the enable. The decision requires 80 failed samples within 100 total samples on a 12.5-millisecond loop. A single low snapshot without enable status does not reproduce the full diagnostic result.

Use the applicable circuit procedure to assess why the signal remains below its allowed bound. The row identifies low direction but cannot by itself separate an input-circuit fault from a problem within the switch or associated electronics.

Verification should demonstrate permitted signal values for the actual hood states and a completed monitor without recurrence. The code does not certify latch security, and the source does not mandate switch replacement. It lists Type B, two-trip behavior for this strategy.

Source and applicability

Confirm the reporting module, system and calibration before applying these diagnostic limits. GM diagnostic table, PDF page 660.