How to Diagnose a Faulty Alternator in Your Car

A faulty alternator can cause you all kinds of problems if you are not keen enough. However, how do you diagnose a faulty alternator?

Symptoms of a Bad Alternator

A car with a faulty alternator may have the following issues;

Service Engine / Battery Light

When the alternator starts to fail, it will light up a “Check Engine”, “ALT” or a battery icon indicator.

Dead Battery

A bad alternator leads the vehicle to use up all of the battery’s capacity. This leaves it drained.

Dim Lights

A failing alternator will show through dim lights or flickering. This is easily noticeably at night through the headlights.

Engine Stalling

An engine can suddenly cut while you are driving. A faulty alternator maybe responsible.

Electrical Issues

Car equipment like power seats or windows will start failing/become too slow. This shows there’s lack of enough power.

Weird Noises

The vehicle may have weird noises that come from serpentine belt. It could may not be spinning the alternator pulley efficiently hence lack of charge.

How to Tell if Your Alternator is Bad

You maybe at crossroads on whether the battery or alternator is faulty. This can be easily determined through the following;

Have a Specialist Test the Alternator with Equipment

To have a definitive answer to your alternator question, you need to have your vehicle checked by a professional. This can be done with the use of a digital charging system analyser or a carbon pile load tester. Professional repair shops have these equipment.

Check Charging System Output Yourself with a Digital Multimeter

You can perform the basic charging system output test all by yourself. You just need to have a digital multimeter set to DC volts.

Connect the black meter lead to the negative battery terminal and the red meter lead to the positive battery terminal. When the engine is off, the battery should have a base reading of at least 12.2 volts.

Start the engine and increase the speed to 1,500-2000 RPM (depending on your vehicle). If the alternator is okay, the reading will be 13.5-15.0 volts. Make sure the lights and accessories are turned off.

In case you have doubts, consult a specialist.

Read also; A guide to finding the Best Car battery

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