How To Diagnose Alternator Problems


The alternator of your car is an essential component of what you need to keep your car running smoothly. In fact, it is the power source of your vehicles, as if your alternator doesn’t work correctly, your car simply won’t run. Although that might sound scary, the good thing about alternators is that when they start to go bad, they will let you know with a number of signs that can be used to diagnose precisely what is wrong.

However, in order to keep from being stranded on the side of the road, you will need to be able to recognize these signs in advance before your alternator gives up all at once. Here are some tips to help you in the diagnosis of alternator problems.

1. First of all, check your console panel to make sure that the bulb for your alternator is lit up and working. In a healthy and properly functioning engine, this bulb will turn on when you start your engine. If it doesn’t, this might mean you have a problem with your alternator.

2. Look for any belts that are worn down in your engine bay. Most alternators run through a series of hard rubber belts that run continuously whenever your engine is turned on. Naturally, after dozens of thousands of miles and exposure to heat, cold, and all kinds of chemicals, these rubber belts will tend to wear down. This is why you want to check the belts out before they snap completely.

A worn belt can lead to a lower electrical output from your alternator. When the output is lower, your battery might not be able to achieve a full level of charge. This is particularly likely to occur when you do things that tax the battery and alternator, such as use the air conditioning unit within your vehicle or turn on your headlights at night.

Similarly, if you are getting a low output or aren’t getting any output at all, you might have a bad connection in your battery or in your alternator. You might also have battery terminals that are getting corroded or your ground connections might be wearing out. Fortunately, any of these problems are typically much cheaper to repair than bad belts, and bad belts are still cheaper than replacing the entire alternator.

3. Look at the alternator belt itself and check for glazing or cracks. Do this only when the engine is cold and not running. If you feel handy, you can try to take in any looseness you find in the belt by following the specific service instructions for your vehicle. Slack belts are more likely to jump and are less efficient than taut ones.

4. Check the terminal connections of your battery as well as the voltage of the battery itself when you have the engine on and idling. Get out the voltmeter and see if it reads somewhere between 15 and 13.8 volts, which is the span of charge for fully charged batteries. If you consistently get readings that span 13 to 12.8 volts, you might have a battery problem or a malfunctioning alternator.

5. Finally, listen to the alternator and see if you hear a grinding noise that is very loud. This suggests the rotor inside the alternator is failing. If this is the case, you will likely need to replace the entire alternator.

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