How to know if an alternator is failing?

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An alternator on a car engine is essentially the generator. The purpose of the alternator is to convert gasoline into energy that can power the electrical components of your vehicle, including replacement of the battery power. The alternator is essential to keep the car running for a long time . With a little observation, it is easy to know when an alternator is failing and needs to be replaced before it becomes a real problem.


  1. Keep attention in light of the “battery” or “alternator”. This light should appear on your dashboard when the car is turned on (if not, you may have blown), but should not be on when you are driving. If it does, it is a sign that something is wrong with the alternator or battery.
  2. Turn on the turn signal. If it blinks at a slower pace than the other, or if it is blinking at a slower than normal speed, the alternator may be the real culprit. Other possible signs that the dash lights are dim or flashing are included, the power steering stops working (the wheel becomes stiff) or attenuation of the light beam.
  3. Listen to your engine. A birdie from the alternator can be a sign that the bearings are wearing out. A loud squeal can also be indicative of a failure of the alternator or the alternator belt is worn.
  4. Check your alternator. If you do not know where your alternator is, look at the label with the configuration table of the pulley on the front of the engine. The alternator is labeled ALT,alternator, or GEN generator. The alternator is near the front of the engine. Once you find the alternator, if the belt is worn or thin, or if there are chips on the alternator belt, then you should replace the belt. Also it could be a sign that the alternator is failing.
  5. Use a voltmeter set to DC scale. Place the red wire to the positive terminal of the battery and the black cable to the negative or ground. Start the car and turn off all accessories (heater, radio, lights) . Rev the engine. The voltage should be around 14 volts. If less than 12, then there is a good chance you have a faulty alternator. Turn all accessories and check the engine again. If the voltmeter reads less than 13 volts, then there is a good chance that your alternator is bad. Most auto parts stores are willing to do this for you for free.
  6. Remove the alternator and do a review of the discharge. This will be the final and definitive test. If you cannot get it out of your engine and take it to an automotive shop, need a mechanic to perform this test.

Tips and Warnings

If you had to make your car start at second several times in the last week to get it going, then you should check the alternator and battery.

Always be careful when considering the engine while it is running.

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