Here's why:
* Alternator's Role: The alternator's job is to recharge the battery while the engine is running. It provides power to all the electrical components in the car.
* Faulty Alternator Symptoms: A failing alternator can't produce enough power. When this happens:
* Dimming Headlights: The headlights (and other electrical components) draw power from the battery. If the alternator isn't charging the battery, the battery's power is depleted, leading to dimming lights.
* Fluctuating RPM: The car's computer relies on a steady power supply. A failing alternator's erratic power output can cause the computer to receive inconsistent signals, resulting in the RPM needle jumping around, especially when the engine is idling (putting more load on the battery). This is because the engine's computer might be trying to compensate for the power fluctuations.
In short, these are classic symptoms of a failing alternator. While other issues *could* cause similar symptoms, a faulty alternator is a very strong suspect in this scenario. You should have the alternator tested as soon as possible to confirm.
