Your alternator is part of the system that delivers electricity throughout your vehicle, powering the headlights, interior lights, and accessories. Driven by the crankshaft, the alternator is usually located near the front of the engine. Usually your alternator won’t simply quit without warning—most drivers notice subtle signs over time.
- Flickering battery light: Your battery light doesn’t simply indicate a problem with the battery itself. The light comes on when the alternator’s voltage output doesn’t fall within a specific range. If the alternator isn’t working properly, the battery light may flicker on and off as the alternator’s output wavers.
- Dim lights: Think about a flashlight with a dying battery; the light slowly dims over time, until it finally goes out. Your internal lights and headlights may do the same thing as the alternator fails to provide adequate power for all the car’s systems.
- Extremely bright lights: As an alternator goes bad, it may also produce power surges. These surges can cause the car’s lights to suddenly become extremely bright. The effect is usually temporary.
- Strange noises from under the hood: The noises most commonly associated with alternator problems are growling and whining. A clicking noise may also occur when you try to start the car. That sound is the starter trying to connect the alternator to the battery.
- Unpleasant odor: When the alternator works too hard, it heats up. As a result, the connecting wires may overheat and melt or burn. The smell of burning rubber or hot wires alone isn’t enough to diagnose an alternator problem, but in conjunction with other signs it can indicate a bad alternator.
- Dead battery: Maybe you just jumped your car, and the battery is already dead. This occurs when the battery tries to “pick up the slack” for the alternator and provide long-term power to the car. If the battery’s voltage is still fine, the alternator may be to blame for the dead battery.
- Failure of accessories or instruments: The electric windows may stop working, the radio may cut out, or your cell phone won’t charge from the cigarette lighter. Newer cars are programmed with a priority list of what gets power first. These non-essential items are the first to go.
When the alternator finally fails for good, your car simply won’t start and you could end up stranded somewhere. If you suspect a problem with your alternator or the other connected elements, schedule an appointment with your mechanic.