What happens when the ignition switch is placed in the 'ON' position?

When the ignition switch is placed in the 'ON' position, the primary circuit of the ignition system is energized. This action creates a path for electrical current to flow through the primary winding of the ignition coil, allowing it to build up a magnetic field. By breaking the primary to earth circuit, the switch ensures that the ignition coil can perform its necessary function of generating a high voltage in the secondary winding when the points open.

This is crucial because if the primary circuit were not properly managed, it could lead to issues such as continuous current flow that might prevent the ignition coil from functioning correctly. Not only does breaking the primary to earth circuit facilitate proper ignition timing and operation, but it also helps ensure that the engine can start and run effectively.

Understanding this process is key for troubleshooting ignition systems and diagnosing any related issues that may arise in engine performance.