Here's how the ignition system typically works:
1. When you turn the ignition key or press the start button, the battery supplies electrical power to the ignition system.
2. The ignition switch sends a signal to the ignition coil.
3. The ignition coil receives the electrical signal and uses it to generate a high-voltage electrical current.
4. The high-voltage current is sent to the distributor or directly to the spark plugs (depending on the vehicle's ignition system).
5. The distributor (if present) routes the high-voltage current to the appropriate spark plug based on the engine's firing order.
6. The spark plugs receive the high-voltage current and create a spark across the gap between the center electrode and the ground electrode, igniting the air-fuel mixture in the engine's cylinders.
In modern vehicles, the ignition system is typically controlled by an engine control unit (ECU) that precisely controls when the spark plugs fire based on various factors such as engine speed, load, and temperature.
When you turn on the ignition but don't crank the engine, the ECU usually does not initiate the ignition process, and hence there should not be any sparks at the spark plugs.
However, it's worth noting that some older vehicles or vehicles with certain aftermarket ignition systems may have different behavior, so it's best to refer to the specific vehicle's service manual or consult with a qualified mechanic for accurate information.
