P2826: solenoid J circuit-low and the T87a open-circuit exception

P2826 is classified as pressure-control-solenoid-J circuit-low in this GM table. The monitor compares an electrical voltage with controller-specific thresholds for a ground-short condition. It covers several valve assignments: the nine-speed clutch-select valve, ten-speed default-disable valve and eight-speed boost valve.

A low label is not a universal wiring verdict

The table explicitly says that an open circuit on solenoid I/J can also set P2826 with a T87a controller. That exception materially changes diagnosis: the generic title cannot by itself choose between continuity testing for an interruption and testing for a path toward ground. Correct transmission and controller identification is the first useful discriminator.

The monitor requires an active mapped high-side driver, calibration enablement and qualified supply conditions. Its listed decision uses over 0.30 seconds of failure in a sample exceeding 0.50 seconds. These conditions explain why the fault may not reappear during a brief static check with the valve driver inactive.

Separate electrical and hydraulic findings

A symptom involving clutch selection or pressure may accompany a circuit failure, but this row diagnoses the electrical path. It does not prove a hydraulically seized valve or specify replacement of the valve body. Review the event's driver state and use the exact circuit procedure to distinguish an open load, unintended ground path and controller behavior.

After correction, verify the diagnostic while the mapped driver is operating. A normal pressure reading by itself does not close the electrical diagnosis, and a code that remains absent because the monitor is disabled is not a completed verification.

Source and applicability

Documented 2025 GM gm-2025-04b monitor only; vehicle, engine and controller applicability must be established separately. GM monitor table, PDF page 2313.