What is a common symptom of a failing alternator?

A common symptom of a failing alternator is dim headlights. The alternator is responsible for generating electrical power to keep the battery charged and to supply power to the vehicle's electrical systems while the engine is running. When the alternator begins to fail, it cannot produce sufficient voltage, which leads to a drop in electrical output. This drop can cause the headlights to appear dimmer than usual, as they are not receiving enough power to operate at full brightness.

While excessive engine noise, increased fuel consumption, and unresponsive brakes can indicate issues in the vehicle, they are not directly related to alternator performance. Excessive engine noise might suggest problems with the engine itself, while increased fuel consumption typically points to issues with the fuel system or engine tuning, and unresponsive brakes usually indicate brake system malfunctions. Thus, dim headlights serve as a clear indicator of alternator failure, making it the most relevant symptom in this context.