P2853: Clutch-one pressure discharge performance means pressure below the model here

In this GM implementation, P2853 is clutch-one pressure control too low. One branch requires modeled pressure above 1 bar while the sensor reads below 0.5 bar for at least five seconds. The generic “discharge performance” wording should therefore not be assumed to mean pressure remained too high during release.

A second branch compares the model more generally

The controller also checks excessive absolute disagreement when measured pressure is below the modeled value. That branch uses calibration-dependent difference and time limits referenced elsewhere, which are not invented here.

The monitor excludes pressure-sensor, pressure-control-valve and redundant-shutdown-valve electrical faults. The shutdown valve must be hydraulically on, with no recovery request or relevant adaptive override. Superfill must be inactive and have ended more than 80 ms earlier.

Verification needs the commanded control phase

Retain measured pressure, model output and those control states together. A low pressure during an intentional transition does not by itself reproduce the eligible fault. A normal reading at one later operating point cannot clear both branches. The summary identifies insufficient pressure relative to expected control behavior, but it does not isolate a leak, valve, clutch assembly or sensor as the failed component.

Document scope and source

2025 GM 25OBDG07A Part 2 documented monitor only; its application-matrix filename join is unresolved. No model, engine or universal calibration applicability is inferred. These figures explain the cited controller logic, not a vehicle-specific repair instruction. Match the vehicle’s service information before applying them.

GM physical PDF page 1055, GM physical PDF page 1056.