This article will show you how to do a simple alternator test on your Honda Civic with a simple multimeter. No need for expensive diagnostic testing equipment.
The entire test is explained in a step-by-step manner and can be done in under 10 minutes.
Contents of this tutorial:
One last thing before we start, you'll notice that the photos I'm using in this article show the alternator off of the Honda Civic but this is just to make the explanation of the test easier. When you do the test on your Honda Civic, it will be an on-car test, so don't remove the alternator from the car.
Symptoms Of A Bad Alternator
The most common symptom of a bad alternator are:
- The Charge Light (also known as the Battery Light) will be shining nice and bright on your instrument cluster.
- Whenever you turn on the headlights (night driving), they glow very dim.
- The car won't crank, but when someone helps you to jump start it, your Honda vehicle easily starts.
- You have to constantly charge the battery or get jump starts after which the vehicle only runs for a few minutes and stalls.
ALTERNATOR TEST 1: Testing Battery Voltage With A Multimeter
OK, to get this show on the road, the first thing you'll do is to test the battery's voltage with the engine running. This simple and easy multimeter test will let you know if the alternator is indeed charging the battery or not.
The battery on your Honda Civic has to be fully charged, to be able to successfully accomplish this multimeter test. Why? Well, because the battery has to have enough juice to 1.) crank and start the engine and 2.) keep the engine running for about 10 minutes while you perform this test.
Be careful, the engine will be running. So take all necessary safety precautions. Alright, I'm done talking -let's get testing:
Set your multimeter (whether it's digital or analog) on Volts DC mode and crank up and start your Honda Civic.
With the multimeter test leads, probe the battery terminals. RED lead on the battery positive and the BLACK lead on the negative terminal.
What you're looking for is one of two results:
1.) A steady 13.5 to 14.5 Volts DC.
2.) Or 12.5 Volts DC that will steadily decrease as long as the engine is running.
With the engine still running, you need to turn everything on, inside your Honda Civic, that you can possibly turn on.
For example, turn on the A/C or Heater on high and then eyeball the multimeter. Then turn on the windshield wipers on high, and again take a look at your multimeter. Now, turn on the radio, turn on anything and everything that can be turned on that uses electricity to run.
As you're keeping an eye on your multimeter's display screen, this is what you'll see:
1.) Either your multimeter will register a nice and steady 13.5 to 14.5 voltage (in Volts DC) no matter what you turned on inside the Civic.
2.) The voltage will decrease from 12.5 Volts DC to 10-9 Volts DC the more stuff you turn on and the longer your Honda Civic stays running.
Take a look at the following test interpretations to find out which one best fits your multimeter test results:
CASE 1: Your multimeter registered 13.5 to 14.5 Volts. This is good and it tells you that the alternator is working and is charging the battery and providing enough juice for the electrical needs of your Honda Civic.
No further testing is required, since this multimeter test result eliminates the alternator on your Honda as bad.
CASE 2: Your multimeter registered a voltage that steadily dropped down to 9 Volts. This is a clear indication that your Honda's alternator IS NOT charging the battery.
Replacing the alternator at this point usually solves around 90% of the No Charge Conditions on any Honda Civic around the world. That's right, you could stop testing here and say: ‘The alternator is fried’ and be done but I suggest two more easy tests to be absolutely sure it is bad. For the first test of the two, go to: ALTERNATOR TEST 2.