P0B9A: Sense T and groups of zero battery readings

The cited GM description assigns P0B9A to voltage-sense channel T. It belongs to an open-sensing-line diagnostic that can evaluate relationships among several cell readings. A scan result should therefore preserve the surrounding measurements, not just the value labelled T.

A zero reading is not the whole diagnosis

One documented failure case removes power from a slave measuring ASIC and makes every affected cell reading zero. Other branches compare neighboring voltages: the general sensing-line threshold is a difference above one volt, while the common-power-line branch uses half a volt. These are different measurement patterns, even though a scanner may describe all of them as circuit faults.

GM evaluates the open-line condition over 600 milliseconds, with checks at 200-millisecond intervals. A momentary reading captured outside that window does not establish the monitor's complete finding.

Why other battery-controller faults matter

The source excludes active sensing-module communication, cell-balancing and internal-performance faults. The secondary protection self-test must be inactive, and communication must be enabled. If those conditions are not satisfied, a quiet monitor after clearing memory cannot demonstrate that the T sensing path has recovered.

The source does not provide a universal pinout or channel-to-cell location. Leave high-voltage access to the appropriate technician. Its busbar case includes an unfinished comparison, so no missing voltage limit is supplied here.

Source and applicability

15OBDG01 Hybrid Diagnostics, cited controller and monitor only. Historical calibration limits are not universal specifications; per-code vehicle, engine and hardware applicability must be verified.

GM source, physical page 635 · GM source, physical page 636.