Testing Your Alternator at AutoZone (2024)

Why Test Your Alternator At AutoZone?

If you suspect a bad alternator, there’s no better place to get it checked than AutoZone. If you bring it to your local mechanic or dealership, you’ll need to make an appointment, which could be days away. Then, you’ll need to drop it off or wait for hours without your vehicle until it’s been diagnosed. And once you get the results, there’s an invoice to pay for the alternator testing, regardless if it’s received a passing or failing grade.

An alternator test at AutoZone takes the stress out of it all. Whether you drive your car in for testing or have the alternator out of your car already, there’s no appointment required. It only takes a few minutes, and it’s completely free. Yes, you read that right. Free.

A failing alternator can manifest in different ways. Signs of a bad alternator can include:

  • Flickering or dim lights
  • Battery warning light illuminated
  • Slow electrical operations like power windows
  • Belt squeal or chirp
  • Growling or droning under the hood, related to engine RPM
  • Slow engine cranking
  • And, of course, a dead battery

At the first sign of these symptoms, get to AutoZone. Our alternator test will help you determine what is causing your electrical issues. Our staff will help you find the right parts for your vehicle with brands you trust, like Duralast, and avoid unnecessary costs.

How to Test Your Alternator at AutoZone

If you aren’t sure whether it’s your alternator or battery failing, get a free, accurate alternator test at AutoZone.

Getting your alternator tested at AutoZone is simple and hassle-free. An AutoZoner can test your alternator while its still in your vehicle, saving you the hassle of removing it and re-installing it if it’s still good. Or, if you have the alternator out of your vehicle already, we can test it on the bench instead.

Not sure which location to choose? Luckily, all AutoZone stores can test it for you, and at no charge at all. Find an AutoZone location near you online – the easiest way to get directions, store hours, and see which services they offer.

AutoZone Alternator Testing Procedure

Testing Your Alternator at AutoZone (2)

Alternator Test in Your Vehicle

The first – and easiest – testing procedure is to bring your vehicle to your local AutoZone for an in-vehicle test. One of the friendly staff will connect a portable tester to your vehicle’s battery before starting the engine. Once it’s running, the tester will determine if the alternator is producing sufficient voltage. They’ll also perform a visual inspection and listen for abnormal noises that could indicate the alternator is in poor condition.

Testing Your Alternator at AutoZone (3)

In-Store Alternator Test

The second method is for alternators that have been removed from the vehicle. Using our Duralast DuraTest bench tester, the alternator is connected to a series of leads, and the assembly is spun. The computerized tester analyzes the results and indicates whether the alternator passes or fails, along with more detailed results on the screen.

It checks if the alternator produces between 14.0 and 15.0 volts. But the test isn’t complete there. Output is checked under load as well, mimicking your vehicle’s normal operation with various systems turning on and off, to determine if it keeps up with a load present. If it doesn’t pass either one of the tests, the test result is “FAIL”.

What to Know About Alternator Testing at AutoZone

From start to finish, your alternator test at AutoZone only takes a few minutes. After the quick and easy test, we’ll help you find the perfect replacement for a failed alternator from our vast selection in-store and online.

If the alternator passes, but you’re having trouble starting your car, it could be one of a few other issues. You might have a bad battery, a faulty starter, or even something as simple as a burnt fuse or fusible link that requires further diagnosis. Fortunately, we perform free battery and starter testing too!

What to Do If Your Alternator Fails the Test

Your alternator failed? AutoZone has a wide selection of new and remanufactured alternators to choose from. Regardless of what make or model you drive, we’re sure to have a solution for you. Install a new alternator yourself, or purchase an alternator from AutoZone and bring it to a mechanic of your choice.

For certain parts, like the alternator bearing, brushes, diode, or resistor, it may be possible to rebuild the alternator rather than replace it completely. This type of repair is for a more advanced DIYer, as it must be fully disassembled, the faulty parts replaced, and the alternator reassembled precisely.

Keep in mind that a replacement carries a warranty on the assembly – peace of mind above and beyond what you get with a repair. And for Duralast alternators, enjoy our Limited-Lifetime Warranty.

Maintenance Tips to Prevent Alternator Issues

Trying to prolong your alternator’s lifespan, or want to keep your new alternator in the best condition possible to avoid a premature replacement? Here are some tips:

  • Check for loose connections regularly. They can cause high resistance and strain the system.
  • Keep the battery terminals clean. Corrosion can interfere with charging and strain the alternator.
  • Avoid adding accessories that draw large amounts of electricity to avoid overloading the system.
  • Charge, don’t jumpstart. While jumpstarting can get you back on the road quickly, it stresses the alternator as it tries to replenish the battery. Slowly and steadily, charge the battery instead.
  • Maintain a healthy battery. If the battery is failing, it can take out the alternator, too. Replace the battery to prevent the issue.
  • Check belt tension and replace bad belts. A slipping belt can prevent the alternator from charging properly.

Visit any AutoZone location for a no-charge alternator test. We offer free parts testing for batteries, starters, and alternators. And when you need a new alternator, we have What It Takes To Do The Job Right.

FAQ/People Also Ask

What is the easiest way to test an alternator?

It’s possible to test an alternator’s voltage output with a multimeter, but the easiest way is with AutoZone’s free in-vehicle alternator test.

Are AutoZone alternator tests accurate?

Yes. AutoZone uses professional-grade equipment to perform alternator testing, whether for bench tests or for in-vehicle tests.

Does AutoZone do free battery and alternator tests?

There’s no charge for AutoZone’s battery, alternator, or starter tests.

How long does it take to test an alternator at AutoZone?

Typically, your alternator test will be completed in under five minutes with an accurate pass or fail grade.

Testing Your Alternator at AutoZone (2024)

FAQs

Can AutoZone test your alternator? ›

Getting your alternator tested at AutoZone is simple and hassle-free. An AutoZoner can test your alternator while its still in your vehicle, saving you the hassle of removing it and re-installing it if it's still good. Or, if you have the alternator out of your vehicle already, we can test it on the bench instead.

Can I test my alternator without removing it? ›

First, test it with the engine turned off.
  1. Turn the engine off.
  2. Turn on your voltage meter and set it to DC volts.
  3. Connect the positive lead to the positive terminal (+) on the battery, then connect the negative lead to the negative terminal (-) on the battery.
  4. Check the battery voltage on the voltage meter.

Can an alternator pass a test and still be bad? ›

Keep in mind, just because the Alternator tests fine, does not mean the system is fine. The charging system is composed of wiring that not only supplies the battery and system with DC power, it also “senses” the voltage that's out in the system in order to properly set the voltage leaving the alternator.

How much does AutoZone charge to check the alternator? ›

To verify that your alternator has gone bad, take it to your local AutoZone store where we can perform a quick test for free. If you're ready to replace your alternator or just want to see basic information on performing the job, watch our video on how to install an alternator.

What are the symptoms of a bad alternator? ›

How Do You Know if a Car Alternator is Bad?
  • Trouble starting your car.
  • Frequent stalling.
  • Whining or screeching noise after the vehicle starts.
  • Dim or overly bright lights.
  • Smell of burning rubber or wires.
  • Dead battery.
  • Battery dashboard warning light is on.

Can you jumpstart a car with a bad alternator? ›

Yes, you can, but there are crucial considerations: It's a temporary fix. Jumpstarting a car with a bad alternator is a temporary solution. While it can get your vehicle running again, it won't fix the underlying issue, which is the failing alternator.

How do you check an alternator DIY? ›

Set your multimeter to DCV (DC Volts) above 15. Make sure your alternator's positive and negative terminals are clean. Put the multimeter's black cable to the negative terminal and the red cable to the positive terminal. Look for an ideal alternator reading of around 12.6.

What battery cable do you take off to check the alternator? ›

The voltmeter or multimeter should read between 13.5-14.5 volts if the alternator is functioning correctly. If you are trying to remove a battery cable to test the alternator, it is important to remove the negative battery cable.

Does disconnecting the battery test the alternator? ›

You don't need to. If you disconnect the battery on a running engine and it stays running, the alternator is proven to be working. If it wasn't the engine would dye. This test will not tell you what the output is but it will tell that there is at least enough power to keep the engine running.

Does O'Reilly test an alternator? ›

Our experienced parts professionals can test your starter or alternator while it's still on your vehicle. If your vehicle won't start and you believe the starter or alternator may be the culprit, simply bring the part to an O'Reilly Auto Parts store near you and we would be happy to bench test it for you.

How accurate is an AutoZone alternator test? ›

It's as accurate as the equipment is in good working condition. If possible, I always remove the alternator and bring it in so they can bench test it.

What is the most common cause of alternator test failure? ›

Factors such as heat, vibration, and electrical spikes can eventually cause the alternator to fail. According to Repair Smith, your car's alternator may fail because of: Age and use-related wear. Engine oil of power steering fluid leaking onto the alternator.

How to test if your alternator is bad? ›

How do I test to see if my alternator is bad? Remove the negative cable from the battery while the car engine is running. If the vehicle stalls, the alternator may be bad. Alternatively, use a multimeter to check the voltage generated by the alternator to determine if it is fit for use.

Where can I test my alternator for free? ›

O'Reilly Auto Parts' FREE Store Services

Along with free starter and alternator testing, O'Reilly Auto Parts also provides several other free store services, including free Check Engine light testing, wiper blade installation, headlight bulb installation, battery testing, and fluid and battery recycling.

Will AutoZone install an alternator? ›

Does AutoZone do a good job replacing alternators? No, they don't replace them for you. However, if you need yours tested, and can remove it yourself and bring it in, they will test it. Depending on the vehicle, changing the alternator may be pretty quick and simple.

Does Advance Auto Parts do free alternator testing? ›

We will test your battery, starter, and alternator to make sure your vehicle is starting and charging for even the longest road trip. We can test your battery, starter, or alternator on or off the vehicle. This is a free service for all customers.

Can I return a faulty alternator to AutoZone? ›

IN-STORE RETURN POLICY

To return a product to an AutoZone store, return an item in its original condition and packaging, with receipt, within 90 days of the purchase date to request a refund. Return a defective item within the warranty period. Requests for refunds may be denied if the item has been used or installed.

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