What Are the Symptoms Of a Bad Alternator?
When it feels like your car’s battery just can’t stay charged, it might be time for a new alternator.
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Your vehicle’s electrical system is complex, but unless you drive a British car from the 1970s, it is generally designed to “just work.” Even so, things can go wrong, and one of the most common problems can leave you stranded, that being a bad alternator.
A bad alternator can cause a dead battery and other problems with vehicle systems like the stereo and power windows. But there’s good news here, because even an automotive novice can watch a video or two and figure out how to change their own alternator. Perhaps the hardest part of it all is making sure the belt is replaced properly when the job is done.
Every one of The Drive’s crack squad of researchers can count themselves among the ranks of DIY mechanics that have replaced an alternator at home. Trust us, if we can do it, you can do it. Let us take you through the finer points of replacing a bad alternator.
What Is an Alternator, and How Do I Know It's Working?
Your vehicle’s alternator is one of the three major parts needed to generate and circulate electrical power. The alternator uses magnets that spin to create an alternating current that converts energy into electricity. It’s usually found on the front of the engine and is driven by the crankshaft via a serpentine belt.
Your car can communicate with you in many ways, especially if there’s something wrong. If the alternator is starting to go bad, there are a few things to look out for:
- Warning light: The easiest way to know something’s amiss is that there will likely be a battery-shaped warning light in your vehicle’s gauge cluster. A simple OBD2 scanner can help you here.
- Your headlights or interior lights dim or flicker, especially when using the air conditioner or stereo.
- Other parts of the vehicle, like the power windows and door locks, start acting up.
- You hear an unusual clicking or rattling sound.
- Your battery continues to die, even when the vehicle is running.
Here’s How To Fix a Bad Alternator
There are kits and other methods for rebuilding a bad alternator, but we’re going to focus on a replacement instead. It’s easier and more time-efficient. It’s important to note that the steps below are a simplified version of the process. Refer to your vehicle’s service manual for specifics.
Let’s do this!
Replacing Your Alternator
- Pop your hood.
- Disconnect the negative terminal of your vehicle’s battery.
- Loosen the belt tensioner that is near the alternator. This will allow slack in the belt so that both it and the alternator can be removed safely.
- Remove the serpentine belt.
- Disconnect and remove any wiring harnesses or brackets attached to the alternator
- Loosen connecting bolts and remove the alternator.
- Refit the new alternator in place of the old one and reinstall any screws removed in the process.
- It’s a good idea to replace the serpentine belt. Install the new one, making sure to rethread the way it came off the vehicle.
- Reset the belt tensioner. If it’s too loose, you’ll hear a squealing sound, but if it’s too tight it could cause damage to the belt and the unit.
- Reconnect the battery cable.
- Close the hood and test the car.
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