Diagnosing a Dying Alternator: These Tips Could Save You Hundreds
I know no one wants to deal with car troubles. As a former mechanic, I’ve seen plenty of customers come in frustrated, unsure of what’s wrong with their cars. At times, it would be something simple, but it could be something like a bad alternator or something more serious. A dead alternator could potentially leave you stranded and cost you a boatload of money to fix if it’s misdiagnosed. Before you jump to conclusions, you can take a few moments to determine if the alternator is really to blame before you head to the shop.
1. Know the Warning Signs of a Failing Alternator
The very best thing you can do to avoid alternator troubles is to know the warning signs that something’s not quite right. Some of the most common symptoms that it’s on its way out are dimming headlights, flickering lights on the dashboard, and even a battery warning light on your dash. Other potential signs that there is something wrong include electrical issues with your power windows or radio. You should also pay attention to any strange noises or smells. Typically, a bad alternator will make a whining or grinding sound. You may also notice a burning rubber smell. All of this should not be ignored!
2. Test Your Alternator with a Simple Multimeter Check
A multimeter is a handy tool that can help you diagnose alternator problems quickly and accurately. First, set the multimeter to DC voltage and attach the probes to your battery terminals with the engine off. A healthy battery should read between 12.4 and 12.7 volts. Next, start the car and check the voltage again—it should increase to 13.7 to 14.7 volts if the alternator is working properly. If the voltage drops or stays the same, it could be faulty.
3. The Headlight Test: An Easy Backup Method
If you don’t have a multimeter, the headlight test is an alternative way to check your alternator. Start your car and turn on the headlights while the engine is running. If the lights brighten when you rev the engine, your alternator is likely working correctly. However, if the lights dim or flicker, it may indicate that the alternator isn’t generating enough power. This test is quick, requires no special tools, and can give you a good idea of your alternator’s health.
4. Inspect the Alternator Belt and Connections
Sometimes, the issue isn’t with the alternator itself but with its belt or connections. A loose or damaged belt can prevent it from charging the battery efficiently. Inspect the belt for cracks, glazing, or looseness, and make sure it’s properly tensioned. Also, check the electrical connections to ensure they’re secure and free of corrosion.
5. Avoid Common Mistakes When Testing Your Alternator
Many car owners mistakenly replace their battery when the alternator is the real issue. Jump-starting your car and assuming the problem is fixed can also lead to a dead battery and further complications. Using incorrect multimeter settings or misreading the results can give you a false diagnosis. It’s essential to follow testing instructions carefully and double-check your results.
Save Money and Stress with a Quick Check
A dead alternator can be a headache, but you will want to make sure that’s truly the problem before you go in. Sometimes, the symptoms can be something else much cheaper to fix (like a dead battery). Make sure you are aware of the warning signs and use some of these simple testing methods to pinpoint the issue. It will help you save some money by catching problems early on before your alternator completely dies.
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Drew Blankenship is a former Porsche technician who writes and develops content full-time. He lives in North Carolina, where he enjoys spending time with his wife and two children. While Drew no longer gets his hands dirty modifying Porsches, he still loves motorsport and avidly watches Formula 1.