P0BA9: Sense W open-line checks depend on surrounding values

For P0BA9, the cited GM table identifies voltage-sense channel W. The relevant diagnostic is an open-line investigation using relationships among measurements, rather than a direct capacity test or a universal low-cell-voltage threshold.

Look beyond one channel

GM's general sensing-line branch compares neighboring cells with a difference above one volt. The common-power-line branch uses a half-volt difference. A separate note explains that removing power from a slave measuring ASIC can leave every affected cell report at zero. Thus, an isolated disagreement and a group of zero readings are materially different observations for the technician.

The condition must satisfy a 600-millisecond window with 200-millisecond evaluation frequency. Preserve a time sequence where the diagnostic system allows it, rather than treating an instantaneous reading as the complete fault record.

Confirm the monitor was available

Communication must be enabled. Specified sensing-module communication, balancing and internal-performance faults prevent evaluation, and the secondary protection self-test must be inactive. A retest under an inhibited condition cannot establish that W's sensing path is sound.

The channel letter is not a safe guide to opening the pack or locating a connector. The correct hardware mapping and high-voltage service procedure remain necessary. The original table leaves one busbar comparison unfinished; this explanation does not invent the missing value or present a complete battery-disassembly diagnostic.

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.