P2312: Why a low ignition-driver signal needs its command state

P2312 identifies a low ignition primary-control circuit in the generic dictionary. The cited GM monitor checks the voltage while the low-side driver is off. A low observation in that state supports the controller’s short-to-ground classification; it is not a measurement of spark energy.

Read the operating window

The row requires synchronized ignition, engine speed above 1,400 rpm and more than nine ignition-counter increments. Those conditions matter when comparing an idle observation with a stored fault: the documented evaluation is not simply an ignition-on continuity check. The listed confirmation interval is 0.4 seconds, with two-trip reporting.

Resolve the channel before testing

There is an unresolved identification difference: the generic entry says coil E, while this GM row says coil B. Do not turn either label into a cylinder location without vehicle-specific service information. The useful finding is the off-state low-voltage behavior, while the relationship between the naming conventions remains unresolved here.

For verification, preserve driver command and fault status together. A normal-looking signal captured during an on command does not test the same failure condition. This table alone does not establish whether the defect lies in wiring, the connected load or the output stage.

Document scope and source

2025 GM 25OBDG07A Part 2 documented monitor only; its application-matrix filename join is unresolved. No model, engine or universal calibration applicability is inferred. These figures explain the cited controller logic, not a vehicle-specific repair instruction. Match the vehicle’s service information before applying them.

GM physical PDF page 701.