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Home Blog How To Diagnose A Failing Alternator

How To Diagnose A Failing Alternator

The alternator in your vehicle is one of the many accessories that spin based on the rotation of your engine's crankshaft. Your alternator is an essential part of the electrical system - learn more about the specifics of how it works in this post. But when it starts to fail, the issues may not immediately appear to you in the driver's seat. Below, we cover some of the problems you can expect with a failing alternator. We'll also offer a few tips on correctly identifying a failing alternator instead of a failed battery or more pressing electrical issue.

Modern alternators can often last up to 100,000 miles or more before they fail. In a younger vehicle, when an electrical issue pops up, it can be best to assume that it is something other than the alternator. An electrical system issue is often due to a failed or failing battery. Most batteries will only last 3-5 years of use before they go bad. If you're experiencing issues with your electrical system, begin by diagnosing and ensuring the battery is in proper working order. Also, check for blown fuses and loose cables.

Common Alternator Issues

Old new alternator OEM

If you've determined the battery is not the cause of your issue, read on as we highlight some of the more common alternator issues and how you can diagnose these problems. Some of these signs include:

  • Car dies or stalls, even if the battery isn't old.
  • Vehicle can be jump-started but quickly dies when jumper cables are removed.
  • Whining or screeching sound from the engine bay.
  • Battery indicator light on the dashboard is staying on.
  • Voltage no longer reads just over 13V when the car runs.

When it comes down to it, the alternator creates electrical energy that is used throughout your vehicle. If it seems like the car isn't getting enough electricity, and the battery is good, it's likely the alternator has failed. Unless the drive belt or alternator pulley is worn, you won't be able to see anything wrong with the alternator. Alternators often fail because wiring or electrical components inside the alternator housing have gone bad. If you'd like to know more about the alternator and how this part works within your electrical system, check out this post (link to first post in guide) 

OEM Alternators From Suburban Auto Parts

OEM alternator

For any replacement or repairs on your GM vehicle, look no further than SuburbanAutoParts.com. With more than 70 years in business, you can trust all our OEM-level GM parts. All our parts come with a 12-month, unlimited-mile warranty. You can contact us here, or give us a call at 888-287-6125.