P2306: Cylinder 3 ignition control has a ground-short signature

P2306 identifies an electrical low fault in ignition control number 3 in the reviewed GM monitor. The dictionary's coil C terminology maps to cylinder 3 control here, but a vehicle-specific reference is still needed to locate that circuit.

The diagnostic observes the driver circuit

The controller evaluates output-driver voltage against an acceptable range. Its short-to-ground specification is less than 100 ohms between the signal and controller ground. This is an electrical detection criterion, not a test of combustion quality or a universal coil winding-resistance limit.

Monitoring requires a running engine and ignition voltage above 11 V. Fifty failures in 63 samples, taken at a 100-millisecond rate, meet the documented decision rule. Supply voltage and event duration therefore matter when comparing a recorded fault with a later inspection.

One source limitation affects reproduction

The strategy says the low-side driver is checked while powered off; the malfunction column says the relevant voltage occurs during the on state. Both statements appear in the same row. The correct state must be resolved with the applicable service procedure before attempting detailed electrical verification.

A low signal alone does not identify whether wiring, a connected component or the driver is responsible. Nor does P2306 establish that a spark plug or mechanical cylinder fault caused the event.

After repair, confirm the cylinder 3 control circuit behaves correctly in the specified test and that the monitor completes without recurrence. The source lists Type A, one-trip behavior without a parts prescription.

Source and applicability

The documented control architecture and calibration require confirmation for the vehicle being diagnosed. GM diagnostic table, PDF page 644.