What happens in a magneto ignition system when the ignition switch is placed in the Off position?

• A. The primary circuit is connected to ground.
• B. The secondary winding is energized.
• C. The spark plug is grounded directly.
• D. The magneto is bypassed by the starter.

Answer: (A)

In a magneto ignition system, turning the switch to Off kills spark by grounding the primary circuit. The magneto generates spark by building current in its primary winding and then releasing that energy to the secondary when the points open. If the ignition switch grounds the primary, current cannot flow, the magnetic field cannot be established, and there’s nothing to collapse to produce a high voltage. With no energy in the primary, the secondary winding won’t fire and the spark plugs won’t spark. This is why grounding the primary circuit is the effective way to stop ignition; other scenarios would either energize the secondary, short the plug, or involve unrelated bypass paths that don’t control the magneto’s output.