What component is primarily driven by a serpentine belt?

The alternator is primarily driven by the serpentine belt in a vehicle's engine system. The serpentine belt is a crucial component that connects multiple accessories to the engine's crankshaft. As the engine runs, the crankshaft turns the serpentine belt, which in turn drives the alternator.

The alternator is responsible for generating electrical power to recharge the vehicle's battery and support the electrical systems while the engine is running. It converts mechanical energy from the engine into electrical energy, which is essential for ensuring that the vehicle's battery remains charged and that all electrical components, such as lights and the infotainment system, function properly.

In contrast, the other components mentioned in the question do not rely on the serpentine belt for their operation. The fuel pump is typically driven by the engine's mechanical systems or is electric, the exhaust manifold is a stationary part of the engine that exhaust gases pass through, and engine coolant circulates through the engine and radiator, which is a separate system entirely from the belt-driven accessories. Understanding the role of the serpentine belt and its relationship with the alternator is vital for troubleshooting electrical problems and maintaining the vehicle's performance.