P0B74: a circuit L low report is based on two block values

The cited GM row identifies P0B74 as block 12 voltage measurement out of range low. Its generic circuit L title is a shorthand for that diagnostic channel. The source does not define a universal physical battery layout for every vehicle using the same code number.

What to ask for in the diagnostic record

The published condition is block 12 below 2 V together with block 13 below 2 V. A useful record therefore includes both channels, their timing and the controller state. A single low number without the neighboring value does not demonstrate the complete monitor decision.

Fifteen failing samples out of twenty are required, using a 100 ms sampling interval. This filtering should be distinguished from the two-trip Type B reporting classification listed in the table.

A cleared code is not a completed monitor

The low-range check requires BPCM RUN mode, a 12 V system supply in the 9–18 V range, and no active P0A1F. If a later scan occurs outside those conditions, absence of a fresh fault is inconclusive.

The paired low reports should be assessed with the applicable sensing-circuit and battery procedures before attributing the issue to a particular component. The monitor table supplies no repair price, component location or mandatory replacement. A trained hybrid technician must handle any work that exposes high-voltage connections.

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 228.