Electrical System Symptoms:
* Dim headlights: This is a classic sign. The lights will dim, especially when the engine is idling and other electrical components (like the heater fan, wipers, or radio) are turned on. Brightening when you rev the engine points strongly to the alternator.
* Dashboard warning lights: Check your dashboard for a battery light (often a picture of a battery) or an alternator light. These will illuminate if the alternator isn't charging the battery properly.
* Radio/Interior lights flicker: Similar to dimming headlights, flickering interior lights or the radio cutting out intermittently are signs of inconsistent power supply.
* Electrical components failing: If other electrical components are acting erratically (power windows, power locks, etc.), it could be due to low voltage from a failing alternator.
* Car won't start: If the battery is completely drained, it won't be able to crank the engine. This is a late-stage symptom.
Other Potential Signs (Less Direct):
* High-pitched whine or squeal: You might hear a high-pitched whine or squeal coming from the alternator, especially when the engine is running. This is due to the bearings wearing out.
* Overheating: Although less common, a failing alternator can overheat, especially if its internal components are failing. You might smell burning or notice excessive heat around the alternator.
Important Note: Some of these symptoms can be caused by other issues (like a bad battery or a faulty wiring harness). If you suspect a failing alternator, it's best to have it tested by a mechanic. They can use a multimeter to check the alternator's output voltage while the engine is running, providing a definitive diagnosis. Don't wait until your car completely fails to start; address alternator issues promptly to avoid stranding yourself.
