P07B3: Park-button switch A reads below its allowed range

P07B3 is labeled a transmission Park-position switch A circuit-low fault. The reviewed GM row identifies the monitored input more precisely as the Park button's measured switch A signal. That distinction keeps a selector-input problem separate from confirmation that the transmission's mechanical park mechanism has engaged.

The published decision

The low-signal condition is a measured value at or below 115.00. The source supplies no voltage unit for that value, so interpreting it as 115 volts, 1.15 volts or a universal scan-tool percentage would be unsupported. Its meaning is bounded to this controller's signal representation.

Failure qualification requires 20 failing samples within 25 samples. The software loop runs every 25 milliseconds, and reporting is Type B over two trips. A brief low sample and a qualified fault are therefore different evidence; a stable-looking later reading does not erase the earlier sampled event.

What to confirm

Calibration enablement must be active. When reviewing the fault, identify switch A's actual measured signal and the diagnostic's status, rather than using only a displayed Park selection. If a tool exposes a converted quantity, the applicable service information must establish its relationship to the raw monitor threshold.

Confirmation should show that the switch A check executes without repeated low-range samples during the required functional test. The page gives no circuit pinout, component-location claim or replacement instruction. Its limits apply only to the documented 2025 GM monitor until the exact vehicle calibration is established.

Source: GM monitor, PDF page 646.