How to Test Alternator without Multimeter

In 2022 and more contemporary years, we see that cars crucially need electronic components to function properly. One of these is the alternator and not everyone knows exactly what it is or how it works.

When problems arise with it, how then are they solved? A multimeter proves to be a useful tool but even this may not be owned by you or everyone. 

This article solves your problem as it tells you what an alternator is and shows you multitudes of methods to make a diagnosis on it without the use of a multimeter. Let’s get started.

What Is An Alternator

An alternator is a component in your vehicle that produces Alternating Current (AC). It converts chemical energy (fuel) to electrical energy and powers every electronic component in your car. 

You may be wondering what the battery is there for if the alternator does this.

The battery only helps to start your car. Once the car is fired up, the alternator takes over and powers every electronic component in your vehicle, including your lights, air conditioning system, and speakers, among others. It even keeps the battery charged.

If the alternator is bad, expectedly, your car’s electronic system is bound to be dysfunctional. From this, the importance of an alternator becomes evident.

A multimeter is one of the best tools to use to test whether your alternator is in good condition or not. However, it may not be accessible to you at all times. 

Once you are stranded, for instance, how do you make a diagnosis on your alternator? 

Symptoms Of A Bad Alternator

The following occurrences point to a faulty alternator.

• Dimmer, unusually brighter, or flickering headlights
• Failed or difficult engine start
• Malfunctioning accessories (vehicle components that use electricity)
• The battery warning light popping up on the dashboard

How To Test Alternator Without Multimeter

To test an alternator without a multimeter, you see if it gives off a squealing sound, check if a jump–started car stops working after disconnecting jumper cables, or disconnect the negative battery terminal while the engine is running.

There is more to these and a lot of other methods. 

1. Battery Test

Before fully suspecting your alternator and diving into it, it is important to note that your battery could be the problem. This is especially if it is old or the main problem you have is your vehicle not starting. 

In this case, what you want to do is check the connections between your battery and the alternator. Loose or corroded connections at the battery terminals could prevent the functional passage of electric current. 

If the battery is good, but the car fails to start or shows the symptoms mentioned above, then the alternator may be faulty. Alternatively, there are other ways to check for a bad alternator with the use of your battery.

Firstly, if the battery keeps dying, then the alternator is suspect. 

Another way to check is to start up your car and disconnect the negative terminal of the battery. You want to take extra caution while doing this and if the alternator is bad, the engine dies when the terminal is disconnected.

2. The Jumpstart Method

This is a way to take the battery out of the whole picture and work with the alternator alone.

When you jumpstart a car without the battery and with a good alternator, it is expected to keep working even when you remove the jumper cables.

With a bad alternator, the car goes off immediately.

3. Listen For Alternator Squealing 

When the engine is idle, you listen to sounds from beneath the car hood and try to notice a squealing sound coming from the alternator. This may signal a loose serpentine belt.

4. Magnetic Test

The rotor and stator in an alternator produce an electro-magnetic field when they are working. There are cold and hot test methods for this and to conduct the tests, you need a metal tool like a screwdriver.

• Cold Test: Here, you turn your engine ignition to the “On” position without starting the car and use the metal tool to touch your alternator. If it sticks, there is no problem but if it doesn’t, then your alternator may be faulty.
• Hot Test: Here, you keep your engine on and at an idling RPM of 600 to 1000. You then use your tool to check whether there is any magnetic pull from the alternator.

If this isn’t clear, this video paints a vivid picture.

5. The Voltage Gauge Test

If your car has a voltage gauge, you simply rev up your engine and check to see whether the gauge fluctuates slightly. If it doesn’t or reads low while your engine is revved up to 2000RPM, then the alternator may be faulty. 

6.  The Radio Test

Your radio can also be used to conduct a simple test on your alternator. What you do is switch it on, tune the radio to its lowest volume and frequency, and listen to it closely. 

If you hear a buzzing sound, your alternator may be bad. 

7. The Accessories Test

“Accessories” refers to your car components that make use of electronic Emery or power to function. These include your speakers, windshields, air conditioning system, interior lights, and radio, among others. 

If a number of these accessories are malfunctioning, your alternator may be the culprit.

Fixing A Bad Alternator

Applying fixes to your alternator isn’t all that difficult as it is one thing you could do yourself. All you need is a serpentine belt diagram as well as repair information specific to your vehicle to use as a guide.

Thankfully, these can be easily found online.

Regardless of this, taking your device to an auto-repair shop places it in the hands of professionals and isn’t much of a costly thing to do.

Frequently Asked Questions