Home / Car Symptoms / Symptoms of a Bad Alternator | 10 Failing Warning Signs

Symptoms of a Bad Alternator | 10 Failing Warning Signs


When your car wont start, most consumers consider the battery first and jump to the conclusion they need to replace the battery. This step could be an expensive mistake. While it is true that the car battery is not fully charged and does not have enough power to start your engine, the real question is why is it not fully charged?

As batteries age, they become less efficient, and they eventually fail — a dead battery is one of the many universal symptoms of a bad alternator. However, numerous other electric failures could be causing an otherwise good battery to have insufficient power to start your car.

For example, common symptoms include a bad or failing alternator, a broken belt or slipping belt, or perhaps a short circuit somewhere in the cars electrical system. These can all lead to a dead battery or one without sufficient electrical power to start your engine. We explore the causes of a dead battery and how to diagnose this situation.

What is an Alternator?

The alternator is a crucial component in the electrical system of your car. It restores the power that your car battery has lost while it is supplying the entertainment, climate, engine management and many other systems with the juice that they require to run correctly by recycling the power it uses while you are driving.

A faulty alternator can create a cumulative effect of numerous electrical problems that can eventually cause your vehicle to breakdown when it begins to fail. The question, therefore, is how you will know when your alternator is failing. Well, the following are the symptoms of alternator going bad that you should watch out for to prevent your alternator from failing.

Top 10 Failing Signs of a Faulty Alternator

Man fixing failing electrical components on a automobile

  1. Flickering or Headlights Dimming
  2. Visual Signs of a Worn Belt
  3. The Indicator Light or Check Engine Warning Light
  4. Odd or Strange Noises
  5. Weak or Dead battery
  6. Weird Smell of Burning
  7. Car Shakes While Driving
  8. Cooling System or Air Conditioner Problems
  9. Electric Failures Due to Loose Wire Connections
  10. Car Wont Start and Has Stalling Symptoms

1. Flickering or Headlights Dimming

If your headlights, dome light or even dash lights are dim or flickering, the alternator is usually the culprit. Your windshield wipers may operate more slowly than usual. Another sure sign, do your dim lights brighten as you increase the RPM?

These are early warning signs of a failing voltage regulator or alternator. The alternator forms part of your vehicle’s electrical system. Its vital role is the provision of power to enable the ignition, starter, and all of your car’s electronic accessories to operate.

You might start noticing that your dashboard lights and/or headlights are starting to dim if it begins to die. As soon as the headlights or dash light dim, this is a clear indication that your alternator might start to malfunction.

Other electric failures like power seats and/or power windows may begin to operate more slowly as compared to the way they usually do when there is signs of a bad or failing alternator.

2. Visual Signs of a Worn Belt

The belt driving the alternator could also be worn or loose. If the belt is missing, shiny from slipping or making a squealing noise, especially when you depress the gas pedal, it may need adjustment.

If you see the warning light coming on, it can be signs of a worn belt, dead battery or alternator. Always due the factory recommended maintenance to your vehicle.

If the electrical system of your vehicle is experiencing problems, the alternator might not be experiencing any problems because one of the belts that is connected to it could be the problem.

You should do a visual inspection of your vehicle’s engine compartment in order to determine if one of the belts is too tight or too loose. You should also be able to spot if a belt is worn or cracked.

3. The Indicator Light or Check Engine Warning Light

The check engine light coming on your dashboard illuminates if your car’s engine control module detects an alternator problem. Some vehicles have an alternator warning light, and this could also be illuminated. Use a code reader to confirm the error condition.

Most modern cars are equipped with a dashboard indicator or warning light that helps in alerting you when the alternator is failing. Although some of the warning lights may say GEN (for generator) or ALT (for alternator), the light coming on will usually be shaped like a battery.

The indicator light may only trigger when you are utilizing multiple electrical components. This generally depends on the amount of electricity your vehicle is using and how much life the alternator of your car has left.

4. Odd or Strange Noises

Slipping belts sometimes generate a squealing noise, especially when the gas pedal is depressed. If the bearings of the alternator are beginning to wear out, they also may make a growling or grinding noise.

Many different parts produce electrical current by spinning inside the alternator of your vehicle. One of these parts could cause a whining noise or grinding noise if it breaks or is worn. Worn out bearings that are inside the alternator usually cause this kind of noise. A whining noise or sound will be produced if the bushings where your vehicle’s alternator is going bad or “faulty alternator.”

5. Weak or Dead battery

Of course, it really could be your battery, especially if it is near the end of its life cycle. However, you need to confirm if the battery is at the end of the life cycle or if the charging system is not working correctly.

Try jump-starting your car and determine if the belts are tight and if the other symptoms mentioned in this post are visible. Installing a new battery with a bad alternator situation can fail to charge the battery and depletes the batteries charge and leaves you stranded again.

A car battery does not last forever because it has a finite life. An alternator can only recharge your car battery to the point where it gives it a decent amount of life that enables it to accept a charge. An alternator cannot bring your car battery back to life if the battery is dead or weak.

You should restart the vehicle by charging the battery in order to determine if the issue is the battery or alternator. Your car will continue to run if the battery is dead or weak. However, the lights will again start to become dim after a while, and this is an indication that the charging system has a significant problem.

The problem is most likely with the alternator if your vehicle is unable to start even after its battery is fully charged. Also, you might have to jump start frequently.

6. Weird Smell of Burning

A serpentine belt loops around the crankshaft pulley on your engine, and also around the alternator pulley as well. If the tensioner on the belt is not applying sufficient pressure, the belt may slip in the pulley and cause it to heat up, causing a burning smell.

A loose or broken belt can be a common cause of weird or burning smells. Always check the condition of the belt driving the alternator.

An alternator works together with a unique system of belts and provides power to the car or truck. If one of the belts does not turn freely, the belt heats up because of the excess friction, and in effect, this leads to the production of burning rubber smell.

If you happen to sense a strange smell that is similar to the one that an electrical fire produces, this could be an indication that the belt is causing inferior alternator output by slipping on your vehicle’s alternator pulley.

You can prevent this by tightening the belt. If you cannot fix the alternator output and strange smell of burning by tightening your belt, it is highly recommended for you to hire a professional to evaluate your car in order to detect symptoms of alternator going bad.

7. Car Shakes While Driving

A car may shake while driving due to the spark plugs misfiring. The alternator provides power to cause a spark. If the alternator is not generating sufficient electricity to power the spark plugs and other electronics in your car, the engine may run roughly.

This can cause the engine to shake while driving or may even be challenging to start. The vehicle may be running on the battery only if belts are broken or if the alternator has failed.

Another sign of a failing alternator is when a car shakes with a particular symptom that it feels that is going to turn off while driving. If you notice the check engine light coming on and some strange dimming lights behaviors when driving you must get you car check out for to eliminate the chances of alternator failure.

8. Cooling System or Air Conditioner Problems

The power steering and air conditioning cooling system is also driven by a belt in the engine. A loose or broken belt can cause the cooling system to stop working. The alternator will also not generate electricity.

The AC can fail immediately if a belt breaks or is not tight enough. You may continue to operate the engine using power from the battery until all of the power has been drained. Check your belts to confirm they are in good condition and are secure.

9. Electric Failures Due to Loose Wire Connections

Loose wires and electrical components anywhere in the vehicles electrical system can drain your battery and cause your alternator to work harder to produce sufficient electricity.

There may be the smell of hot wires as the alternator provides more electricity than needed to overcome the loose connection. If a diode in the alternator fails, the alternator cannot generate DC current, which is what your headlights, dashboard lights, and other electronic systems require to operate in your car.

10. Car Wont Start and Has Been Stalling

There can be many reasons for experiencing difficulty in starting your car. However, a dead battery is one of the significant reasons. If the engine does start, it may run roughly if the spark plugs are not receiving sufficient voltage to ignite a spark. Car owners should investigate why the battery is dead. Check for loose belts or broken belts.

Use a code reader to read the error code if the engine light or alternator light is illuminated on your dash. Verify connections to the battery and alternator are secure. Clean the battery terminals if there is a great deal of corrosion around the battery terminals.

Keeping the battery terminals clean can avoid poor connections. Schedule an appointment with your auto repair shop to check the condition of your electrical system and confirm if your alternator is failing.

Tips on What to do if Your Vehicle Has Signs of a Faulty Alternator

Everything that is failing on your auto alternator are bad symptoms

If you notice that your car is having a common cause of a bad alternator, you should schedule an appointment at a total car care center our auto repair shop for a complete inspection. Also, the mechanic should check the cars electrical system, spark plugs, crankshaft pulley, and make oil changes if needed.

The alternator provides electrical power to your car and serves as a voltage regulator. If you have the necessity to jump start your vehicle on a consistent base, you might want to consider car maintenance done as soon as possible. The weak or dead battery light is a secure sign of a bad alternator.

To extend the life of your car, it is imperative to get oil changes done periodically, and if you notice the check engine warning light on, check the car owners manual to look for a possible universal cause of why your car is having problems. Also, don’t worry If you can’t identify the problem, just schedule an appointment with an auto repair shop to get a diagnose.

What are the most common warning signs of alternator failure?

  1. Burning rubber smell when starting the car
  2. Air conditioning failure
  3. Headlights Dimming while driving
  4. Whining noise from worn out bearings
  5. Electric Failures due to some electrical components


Most total car care centers will clean your cars interior and get a complete vehicle detailed wash, including floor mats and windshield wiper replacement. While you are at the repair shop as you mechanic to check engine oil, and power steering fluid levels.

Hopefully, by reading this post, you can now identify some of the signs of alternator warning or failure. Remember if you notice that your car wont start and there are any dim or flickering headlights, whining noise, dashboard lights on, or any smell of burning wire you might need to schedule an appointment for car maintenance.

Also, a flat tire without the car sensors triggering a signal is another sign of electric failures. Keeping the battery in mint conditions can extend the life of your car or truck.

If you turn on the car, you notice both the battery light and the check engine light on, and there is a possibility that your automobile’s alternator is going bad. Always use factory recommended maintenance suggestions unless something is wrong with your car as a significant transmission repair, burning wire or a faulty alternator.

Last Updated on: January 27, 2023

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Kenneth Gladman
Kenneth Gladman
8 years ago

I have put quite a bit of miles on my older car and the headlights haven’t been the brightest for a while. They have been flickering lately, so I hope it isn’t anything serious with the alternator. I will have to get it checked out.

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