P2865: Low digital output from transmission rod 5

P2865 concerns the digital position signal for rod 5 in the documented transmission. Although the generic title says circuit low, this monitor has two ways to identify a low-side signal failure. Both concern the electrical representation of position, not a direct measurement that the fork is physically too low.

Two low-signal paths

One path detects missing pulses while the input pin is below 2,000 mV. The other sees a duty cycle below 8 percent. The listed confirmation interval is at least 150 milliseconds. These distinctions matter because a completely absent pulse train and an existing but malformed pulse train need different evidence when examined with appropriate diagnostic equipment.

Battery voltage must be within the table's operating window, the engine must not be cranking and the key must not be in the stop state. P0882, P0883, P0652 and P0653 are listed as disabling faults, making supply-related history relevant before interpreting the position channel.

What remains unresolved

The extracted table places contradictory comparisons alongside the VREF2 enable limits. This article does not turn that contradictory pair into a reference-voltage test specification. Confirm the applicable wiring and service information before taking measurements.

For verification, determine whether the original failure was missing pulses or low duty cycle and whether the monitor actually ran afterward. Clearing the code without an eligible signal observation does not establish that either failure mode has disappeared.

Source and applicability

2025 GM 07A-2 documented monitor only; module and calibration applicability must be matched to the vehicle. The application-matrix filename join remains unresolved; no model or engine fitment is inferred. GM PDF, page 915.