Diagnostic article Generic OBD-II
P0ADB: Contactor control-low classification uses high feedback duty
P0ADB identifies a contactor control-circuit condition through a specific feedback encoding in this GM hybrid system.
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Documented application
2009 General Motors diagnostic parameter file 09OBDG08 Engine 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.
The P0ADB row in GM's BAS hybrid table is labeled contactor control shorted low, but its monitored control-feedback threshold is above 98 percent. That apparent inversion is a reason to use the documented signal encoding rather than assume the code name describes a raw connector voltage.
The feedback quantity is not pack voltage
The percentage is the controller's contactor-control feedback. It must not be interpreted as battery state of charge or as a percentage of hybrid pack voltage. The test requires a closed contactor state, an eligible controller state and system voltage above the specified minimum.
The source accumulates 188 failures in 250 samples at a 20-millisecond interval. It also excludes an open service-disconnect status and specified already-failed contactor diagnostics. These qualifications affect whether a valid comparison can run.
Distinguish control feedback from welded-contact detection
P0AA1 separately evaluates failure to achieve electrical separation after opening. P0ADB concerns the monitored control-circuit classification. One does not automatically prove the other.
Preserve the exact feedback and status information for the applicable hybrid service procedure. Do not jumper contactor controls or assume electrical isolation from a status display. Qualified assessment must determine the actual fault. Verification should establish correct control feedback and completed monitoring, together with the prescribed isolation/function checks. Erasing P0ADB cannot demonstrate that either control integrity or safe contactor operation has been restored.
Source and applicability
2009 General Motors diagnostic parameter file 09OBDG08 Engine 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
Hybrid/EV Battery Positive Contactor Control 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