Diagnostic article Generic OBD-II
P07B9: Park-button channel B low-input detection
P07B9 concerns a repeatedly low Park-button switch B reading in the documented GM controller.
Read before applying this article
Documented application
Documented 2025 GM diagnostic parameter monitor in 25OBDG04B.pdf; model, engine and calibration applicability require vehicle-specific confirmation.
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.
P07B9 identifies the B channel of the Park-button input as reading low in the reviewed GM monitor. The A/B label belongs to the selector-switch diagnosis; it should not be used to infer that the mechanical parking lock itself has been tested.
A qualified low reading
The original PDF shows the malfunction boundary as a measured switch B signal at or below 115.00. Twenty failing samples within 25 are required. This is a repeated low-range observation rather than a declaration that every momentary transition must produce a code.
The signal's unit is not printed. A raw value of 115 must not become an assumed 1.15-volt workshop threshold. Confirm the measurement scale in the vehicle's service information before comparing a meter or a converted scan-tool display with the monitor. The actual switch signal and an interpreted selector state are different pieces of evidence.
Verification and limits
Calibration enablement is required, and the row lists Type B reporting over two trips. Unlike the adjacent switch A row, this page does not print a software-loop interval, so the sample count should not be converted to a claimed elapsed time.
A useful verification observes switch B's measured input and whether the monitor completes without a qualified low condition. Merely seeing the letter P on a display does not establish that electrical result. The source provides no part-selection or disassembly instruction. These facts are confined to the 2025 GM table until the installed shifter and calibration are confirmed.
Source: GM monitor, PDF page 649.
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
Transmission Park Position Sensor/Switch B Circuit Low
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