Virginia Auto Service

7 Signs of a Failing Alternator

The alternator is a part of your vehicles electric system. It works with the battery to keep your car moving and all of the lights and electrical systems running. The alternator, essentially, re-cycles the power that your car battery uses while you are driving. It restores the power the battery loses while it supplies your vehicles engine management, entertainment, climate, and other systems with the power they need. Think of an alternator like a cell phone charger, and your car’s battery is the phone. When the alternator goes bad and stops re-charging the battery, the battery eventually dies and the vehicle will no longer run.

7 Signs of a Failing Alternator

Here is a list of seven warning signs to look for in order to help avoid alternator failure:


  1. Dimming Lights

If the alternator begins to go bad, you may notice that your dashboard and/or headlights are becoming more dim.


  1. Electronic Accessories Slowing

The alternator is responsible for providing power to your car’s electronic accessories. When it starts to die, you may notice that your power seats and/or windows operate at a slower speed than usual.


  1. Dashboard Warning Light

Many of today’s cars have a dashboard warning light that will alert the driver when the alternator has a problem. The light is generally shaped like a car battery, however, some lights may say GEN (as in generator) or ALT (as in alternator). Often the light is only activated when you are using multiple electrical components at once.


  1. Odd Smell

The alternator is run by the serpentine belt on the car, and works in conjunction with a system of belts. When a belt isn’t turning freely, excess friction can cause the belt to heat up which can produce a smell similar to burning rubber. If you smell something that is like an electrical fire, it could mean that the belt is slipping on the alternator pulley, resulting in poor alternator output. Often tightening the belt will fix the problem.  Have your alternator checked by a professional if the smell and alternator output are not fixed when you tighten the belt. If the belt brakes or slips completely, the alternator will stop working.


  1. Visual Indications

There are times that the electrical problems you are experiencing are not coming from the alternator itself, but the belts connected to it. You can determine if that is the problem by doing a visual inspection of the engine compartment. You will be able to locate and see visually if a belt is too loose or too tight or if it is cracked.


  1. Failing or Dead Battery

An alternator can only recharge your cars battery if it has a decent amount of life left in it and it is able to accept a charge. If the battery is weak or dead, the alternator will not be able to bring it back to life. To determine if your problem is with the alternator or the battery, charge your battery and restart your car. If it is the battery, the car will start to run but the lights will become dim after a short period of time which indicates a problem with the charging system. If the battery is fully charged and you have difficulty starting the car, the problem is likely with the alternator.


  1. Strange Sounds

There are many parts inside your car’s alternator that spin to produce an electrical current. If one of these little parts breaks or even becomes worn, you may start hearing a whining or grinding noise. Worn bearings inside the alternator are often responsible for such noise. Also, if the bushing that the alternator is mounted to are bad, it will make an unusual sound.


If you suspect a problem with your alternator, don’t hesitate to have it looked at. The power of an alternator can be checked by a mechanic, and replaced or repaired if needed, before you are stranded on the street somewhere.