P0B59: cell-balancing faults can prevent a valid sense-G evaluation

P0B59 identifies voltage-sense circuit G in the cited GM battery-controller table. Its shared open-sensing logic continues onto the following page, where additional enable restrictions are listed.

Read the continuation before calling the test complete

The continued conditions exclude certain cell-balancing faults and internal voltage-sensing-module performance faults. They also require that a separate protection self-test is not running. These restrictions matter when a technician sees that P0B59 did not immediately return after clearing memory.

An inhibited monitor has not demonstrated a healthy G-channel measurement. The absence of a new result must be interpreted with the status of those supporting diagnostics.

The code points to measurement integrity

The family uses adjacent-cell differences and busbar-related observations to recognize open sensing. It also explains that loss of power to sensing electronics can produce multiple zero readings. These patterns do not independently measure remaining battery capacity.

The shared table leaves part of its positive-side busbar criterion incomplete. This draft does not fill that gap or invent a physical location for channel G.

Preserve the G reading, related channel values and supporting-module codes. A trained battery technician should establish the valid operating state, identify the actual measurement-path defect and complete the applicable verification. Replacing a cell merely because its scan label corresponds to G would skip the circuit evidence required by this monitor.

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.