Diagnostic article Generic OBD-II
P27BD: Shift valve two open-load is assessed with the output off
P27BD uses an off-state electrical load check, so a stationary solenoid command does not establish a hydraulic stuck fault.
Read before applying this article
Documented application
2025 GM 25OBDG07A Part 2 documented monitor only; its application-matrix filename join is unresolved. No model, engine or universal calibration applicability is inferred.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
The P27BD implementation here is the open-load check for synchronizer actuation valve two. With its low-side output switched off, the connected load should pull the monitored driver node toward the supply. The driver applies a small diagnostic current; being able to hold that node in its low diagnostic window indicates an open load.
Off-state evidence differs from failed movement
This check concerns an electrical path, not whether a shift rod moved after a hydraulic command. The table requires more than 5 ms of output-off time and at least 150 ms fault confirmation. It also excludes controller safe state and supply faults P0882 or P0883.
A normal-looking current while the valve is actively commanded does not directly repeat the off-state test. Likewise, a rod that fails to move does not by itself prove P27BD’s electrical finding.
What to retain for diagnosis
Preserve the driver’s open-load status, output command and controller voltage together. Use vehicle-specific circuit information to identify the node and load rather than treating the generic solenoid letter as a terminal map. The summary identifies a circuit classification; it cannot distinguish an internal coil opening from a connection, harness or driver problem by itself.
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.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
Pressure Control Solenoid N Control Circuit/Open
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT