P0B84: a high block 15 report needs the correct monitor context

P0B84 is the block 15 high-voltage sensing branch in this GM document. The generic circuit O label should be interpreted through the actual vehicle's controller and battery configuration. A matching code string is not proof that all published calibration limits apply to every hybrid.

The high branch has a narrow meaning

The source sets the range criterion at block 15 above 23 V. It requires fifteen failures out of twenty samples, with a 100 ms interval. This is evidence of a repeated high reported measurement under the monitor's conditions.

The neighboring performance test compares scaled block values with total pack voltage; the low test requires a pair of low readings. Those are separate rules. P0B84 should not be diagnosed by borrowing the criteria of either neighboring code.

Confirm an eligible observation

The BPCM must be in RUN, its low-voltage supply must lie between 9 and 18 V, and P0A1F must not be active. If those prerequisites are missing, a code-free scan cannot establish successful completion of this test.

Retain the block 15 trace and associated faults so a technician can distinguish a real-voltage condition from inaccurate sensing using the proper circuit procedure. The table does not prescribe a replacement battery or authorize direct high-voltage measurements. Physical access and testing require the vehicle's service precautions and qualified personnel.

Source and applicability

GM 2010 10OBDG10 Hybrid Diagnostics, cited BPCM or hybrid-controller monitor only. Historical calibration values are not universal specifications; no per-code model, engine or hardware fitment has been established. GM PDF, physical page 230.