P0B4A: busbar sensing and cell condition must be separated

P0B4A is the voltage-sense circuit D result in the cited GM battery-controller table. Its family strategy concerns an open measurement condition. The table includes both general cell-sensing lines and busbar-side sensing cases.

Busbar-related evidence is not a location map

The source distinguishes positive-side and negative-side busbar sensing. Those are diagnostic configurations, not instructions to assume that channel D occupies a particular side or physical position in every battery pack. The exact channel-to-connector mapping must come from the applicable service information.

The negative-side example combines a busbar-capacitor voltage condition with a cell-voltage condition. The positive-side expression, however, lacks a complete comparison in the printed table. It cannot responsibly be converted into a guessed pass/fail test.

Use the whole monitored pattern

The family also compares adjacent cell readings and describes how a sensing-electronics power loss can affect multiple channels. A technician needs that surrounding pattern before concluding that one physical battery cell is defective.

GM specifies a sustained evaluation window and qualified sensing-module communication. An intermittent change during an unqualified state is useful history, but not a complete reconstruction of the monitor.

Record circuit D exactly as reported, together with surrounding voltages and companion module faults. High-voltage pack access and isolation testing require trained service procedures. The summary establishes the type of measurement problem, while the failed component and physical location remain to be demonstrated.

Application limits

Document-level 2015 GM diagnostic table; per-code vehicle/engine/calibration applicability not established.

Source

15OBDG01 Hybrid Diagnostics, physical PDF pages 635, 636.