P2307: Cylinder 3 ignition control fails its high-circuit check

P2307 is the cylinder 3 ignition-control short-to-power diagnosis in the reviewed GM table. The generic description uses ignition coil C; it should not be used to infer a physical coil position without the correct vehicle information.

Read high in relation to the driver command

The monitor detects output-driver voltage outside its acceptable range while the driver is on. The source gives a short-to-power design specification of less than 100 ohms between the signal and controller power.

This does not mean that any high reading anywhere in the ignition system establishes P2307. The measured circuit, intended output state and controller reference are all part of the definition. It also does not supply a safe instruction for resistance testing an operating ignition circuit.

What changes the weight of a measurement

The engine must be running with ignition voltage above 11 V. The controller requires 50 failed samples out of 63 at 100-millisecond intervals. A normal later reading can miss an intermittent event, while a single abnormal reading does not reproduce the whole decision window.

Preserve the cylinder 3 circuit identity and compare signal behavior with the command using the applicable diagnostic procedure. Separate any accompanying misfire evidence from the electrical fault: this monitor does not evaluate the spark plug, compression or injector flow.

Verification should confirm acceptable on-state electrical response and no recurring diagnostic after completion. The source lists Type A, one-trip behavior but does not determine the replacement component.

Source and applicability

The documented control architecture and calibration require confirmation for the vehicle being diagnosed. GM diagnostic table, PDF page 645.