P058D: battery voltage disagrees with the controller reference

P058D checks whether the battery monitor's reported voltage agrees with a separate system-voltage measurement. In the 04B BCM example, the absolute difference between IBS battery voltage and BCM system voltage must exceed 5 volts for eight seconds in a ten-second window.

A comparison fault is not simply low voltage

A battery voltage value cannot explain this code in isolation. The useful evidence is the simultaneous difference between the two measurements. The 03A ECM example likewise compares the IBS reading with the 12-volt system reference, using thirty-two failed samples out of forty.

Both examples require usable LIN data and exclude separate battery-monitor voltage circuit-low and circuit-high faults. If those prerequisites are not satisfied, a missing or substituted reading should not be treated as the intended two-sensor comparison.

Cranking changes the test context

The BCM description explicitly suspends evaluation during cranking and until a post-crank delay has elapsed because voltage fluctuates strongly during that event. The delay entry has an apparent unit inconsistency, so no exact post-crank duration is asserted here. The supported point is that cranking data and enabled steady-state diagnostic data are different contexts.

Verification should compare the two voltages after the applicable enable conditions return and establish that the discrepancy no longer accumulates. Neither source names a mandatory battery, sensor or controller replacement. The storing controller and vehicle-specific calibration determine the proper service procedure.

Source and applicability

Documented monitors in gm-2025-03a, gm-2025-04b, model year 2025. These are module/calibration examples; vehicle, engine and transmission applicability must be confirmed independently. GM 2025-03a, page 351. GM 2025-04b, page 73.