P254F: Hybrid hood switch faults arise when the two signals agree

P254F identifies an engine hood-switch circuit fault in the cited GM BAS hybrid system. The controller compares two hood-switch signals. Its failure condition is that the signals are equal: both high or both low. This monitored arrangement expects a complementary relationship rather than two identical confirmations.

Why the physical hood position is insufficient

A visibly closed hood cannot establish that both electrical channels are reporting the intended relationship. Likewise, observing one input change does not demonstrate that the second input changed correctly. The useful evidence is the pair of states and their relationship, not simply a single “hood closed” display.

The source specifies the wake-up state on and a 1,000-millisecond failure interval, with a two-trip strategy. A fleeting matching state and a sustained equality therefore are not the same diagnostic observation. Preserve available status and event data rather than inferring the original pair from a later normal reading.

Keep the conclusion within the evidence

The comparison detects an inconsistent switch arrangement; it does not identify a particular contact, connector, harness section or controller as the failed part. The monitor summary also does not establish which physical state corresponds to each channel's high or low value.

Verification should confirm the correct paired states through the vehicle's approved procedure and a completed monitor result. Do not bridge, bypass or defeat hood interlocks to force a preferred signal, especially around a hybrid powertrain. This source supports the circuit-comparison explanation but does not establish a universal hood-latch design or model-specific replacement instruction.

Source and applicability

GM 2009 09OBDG08 Engine Diagnostics, BAS Hybrid section, hood-switch monitor on physical page 123. This dual-signal behavior is scoped to the cited controller; vehicle applicability and channel polarity are not established.

General Motors source, physical page 123