P0581: high cruise-switch input and a misleading table phrase

P0581 is the high analog cruise multifunction-switch input fault in the cited GM momentary on/off switch systems. The strategy and threshold identify a short-to-power range, with an analog-to-digital count ratio of 1.005 to 1.035.

Read the complete source row

The 03A malfunction-criteria text contains a conflicting reference to a ground-related range. Its monitor description, high-input fallback explanation and ratio agree with the clearer 04B short-to-power entry. This article follows those consistent portions rather than treating the contradictory phrase as a separate failure definition.

The ratio is dimensionless. It is not a 1.035-volt upper limit. Both examples specify a two-second failure indication within a 25-second sample period, so the documented decision depends on persistence as well as the input range.

What to verify

Compare the BCM's reported high-range condition with the switch input using the applicable vehicle procedure. The engine controller is acting on information supplied by the BCM; the code alone does not isolate a physical button or controller as defective.

Cruise is disabled for the remainder of the key cycle once the failure occurs. Recovery of the instantaneous input may therefore precede recovery of cruise availability. The two source files use different diagnostic classifications, Type C/no MIL versus Type B/two trips. Applicability and lamp behavior must be established from the exact calibration, while verification must demonstrate that the high-range condition no longer accumulates.

Source and applicability

Documented monitors in gm-2025-03a, gm-2025-04b, model year 2025. These are module/calibration examples; vehicle, engine and transmission applicability must be confirmed independently. GM 2025-03a, page 346. GM 2025-04b, page 565.