P0B86: Voltage-sense P and the open-line pattern

P0B86 identifies voltage-sense channel P in this GM battery controller's open-sensing-line diagnostic. The controller is interpreting a pattern across measurements; the code alone does not prove that the corresponding battery cell has lost capacity.

Why neighboring readings matter

The general sensing-line branch compares adjacent cell voltages. Its documented difference threshold is greater than one volt, sustained through a 600-millisecond observation window. A common-power-line branch instead uses a half-volt difference. The manual separately explains that losing an individual ASIC supply can make all affected readings zero. These patterns distinguish a sensing-path investigation from a conclusion based on one displayed voltage.

The channel letter must be matched to the correct pack's service information. The table supplies no universal connector cavity or physical cell location for P.

Establish that the monitor could run

Evaluation requires enabled communication and excludes specified sensing-module communication, balancing and internal-performance faults. The secondary protection self-test must also be inactive. A missing repeat result while those prerequisites are blocked is not evidence of a repaired sensing line.

Preserve the neighboring values and relevant controller faults for a qualified high-voltage technician. Some busbar-case criteria in the source are incomplete, so this article does not supply a complete threshold tree. The supported comparisons are diagnostic evidence, not instructions to open or probe the battery.

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.