What happens to the electrical system when the engine is off?

When the engine is off, the primary source of electrical power in the vehicle is the battery. This means that any electrical accessories, lights, or other components that remain active will draw power directly from the battery. The alternator, which typically generates electricity to recharge the battery and power the electrical systems when the engine is running, is inactive without the engine's operation. Therefore, the vehicle's electrical system relies solely on the stored energy within the battery until the engine is started again. This situation can lead to battery drain if many electrical components are used while the engine is off.

The other choices do not accurately describe the state of the electrical system when the engine is off. The electrical system is not entirely inactive as there are components that can still function using battery power, and the alternator's role in electricity generation is contingent upon the engine running. Additionally, the fuel pump does not operate continuously but rather only when the engine is running or during certain conditions when the ignition is on, further emphasizing that the vehicle's electrical needs are met directly from the battery during engine shut-off.