P07BF: input-speed circuit low is distinct from low input RPM

P07BF is the electrical low-input diagnostic for transmission input/turbine speed sensor A. The cited TCM compares raw sensor voltage with a lower boundary of 0.2500 volt to detect the ground-short condition.

Check the electrical channel, not only speed

The fault is not simply a statement that the turbine is rotating slowly. A zero-RPM report and an electrically low input are different observations. The source links the voltage threshold to a detection specification below 0.5 ohm between signal and controller ground, without identifying the physical cause of that signature.

This distinction is useful when P0717 or P0716 also appears in a diagnostic history: those source monitors evaluate speed activity or drop behavior, while P07BF addresses circuit voltage. The electrical result can affect whether the performance monitors are permitted to run.

Count logic and enable conditions

A failure interval beyond fifty milliseconds advances the counter, and the counter must exceed sixteen. Both run/crank and battery voltage must be above 10 volts for more than five seconds. Service fast learn, code-clear activity and active P07C0 are excluded.

Verification needs a passing electrical test under those conditions, not merely a momentary return of a nonzero speed PID. Use the vehicle-specific circuit procedure before attributing the code to the sensor assembly. The published resistance relationship is a monitor design criterion, not a live-circuit measurement instruction.

Source and applicability

Documented monitors in gm-2025-03a, model year 2025. These are module/calibration examples; vehicle, engine and transmission applicability must be confirmed independently. GM 2025-03a, page 1122.