Diagnostic article Generic OBD-II
P071A: Transmission mode switch remains active too long
P071A checks prolonged activation of the tow-haul or winter-mode switch in this GM transmission example.
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Documented application
2009 General Motors diagnostic parameter file 09OBDG02 TRANS Diagnostics.pdf. Section-specific modules and calibrations; no per-code model or engine applicability established.
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.
P071A identifies transmission mode switch A, but the documented GM group 02 check is more specific than that generic name. It monitors whether the tow-haul or winter-mode switch remains active for an excessive interval.
Sustained activation is the failure pattern
The published criterion is an active switch state persisting for at least 600 seconds. That is ten minutes of the monitored input being active, not a statement that the selected driving mode has been enabled too long. The physical switch input and the controller's latched operating mode must not be confused.
The diagnostic also has an explicit enable flag. If the vehicle configuration does not enable that switch diagnostic, assumptions based on this table are inappropriate. Its voltage and engine-speed windows further qualify the check.
Record input behavior rather than only the dashboard mode
A useful service record distinguishes the raw switch state from the displayed mode selection and notes whether the input releases after operation. The code alone does not separate a switch contact issue from its wiring or input interpretation.
The table describes a special diagnostic type, not a universal promise about warning-lamp behavior. Use the exact transmission's service procedure to identify the monitored circuit. After correction, verify that the switch input changes and releases as intended and that qualified monitoring completes. A momentary successful mode change cannot exclude a sustained-active fault that occurs intermittently.
Source and applicability
2009 General Motors diagnostic parameter file 09OBDG02 TRANS Diagnostics.pdf. Section-specific modules and calibrations; no per-code model or engine applicability established. This explanation describes the documented monitor, not a universal repair procedure.
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 Mode Switch A Circuit
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