1. Electrical Connection:
- The starter solenoid is connected to the vehicle's battery through a heavy-duty electrical cable, ensuring a reliable power supply.
- When you turn the key in the ignition switch to the "start" position, an electrical signal is sent to the solenoid.
2. Electromagnet Activation:
- Upon receiving the electrical signal, the solenoid's electromagnet is activated. This electromagnet consists of a coil of wire wrapped around a metal core, creating a magnetic field when an electrical current flows through it.
3. Plunger Movement:
- The magnetic field generated by the electromagnet attracts a movable iron core known as the plunger. The plunger is attached to a lever or a shift fork mechanism.
- As the plunger moves, it pushes the lever or shift fork, engaging the starter motor's gear with the vehicle's flywheel. This physical connection allows the starter motor to rotate the flywheel and crank the engine.
4. Electrical Circuit Completion:
- The movement of the plunger also completes an electrical circuit, allowing a high-current flow from the battery to the starter motor. This provides the necessary power to rotate the starter motor and start the engine.
5. Solenoid Hold-In:
- Once the starter motor engages and starts rotating the engine, a small amount of current continues to flow through the solenoid's electromagnet. This maintains the magnetic field, keeping the plunger in its engaged position until the engine starts.
6. Disengagement:
- When the engine starts running, the ignition key is released, interrupting the electrical signal to the starter solenoid. The electromagnet deactivates, releasing the plunger.
- The starter motor's gear disengages from the flywheel, and the starter motor stops operating.
In summary, a car starter motor solenoid acts as an electrical switch and a mechanical linkage, connecting the electrical power from the battery to the starter motor and engaging the starter motor's gear with the flywheel to crank the engine. It plays a vital role in the starting process of a vehicle, allowing the engine to start smoothly when you turn the key in the ignition.
