* Mechanical Connection: The key's movement physically interacts with a lock cylinder. This cylinder is precisely engineered to only turn when the correct key is used (preventing theft).
* Electrical Connections: The key's position activates various electrical circuits:
* Accessory (ACC): The first position often powers accessories like the radio, clock, and interior lights.
* On (RUN): The next position powers more systems, including the fuel pump, electronic control unit (ECU), and other crucial engine components. This allows the engine to be primed for starting.
* Start (START): Turning the key further engages the starter motor, a powerful electric motor that cranks the engine to begin combustion. Once the engine starts, the key can usually be released.
* Immobilizer System (Likely): A 2002 Focus likely has a passive anti-theft system. This means a transponder chip embedded in the key communicates with a receiver in the vehicle's ignition system. If the chip doesn't match the vehicle's programming, the engine won't start even if the key turns the lock cylinder.
In short, turning the key isn't just a simple mechanical action; it's a controlled sequence that sets in motion a chain of events, all meticulously orchestrated to start your Ford Focus' engine. If the key doesn't turn, or if the car doesn't start after turning the key, there could be issues with the ignition switch, starter motor, battery, immobilizer system, or other components.
