How To Test The Alternator (2001-2005 1.7L Honda Civic)

You can accurately test the alternator on your 1.7L equipped Civic DX, EX, or LX with a multimeter.

Not only that, it's easy and fast and in this tutorial, I'll show you how in a step-by-step way.

You can find this tutorial in Spanish here: Cómo Probar El Alternador (2001-2005 1.7L Honda Civic) (at: autotecnico-online.com).

Symptoms Of A Bad Alternator

Your 1.7L Honda Civic's alternator fulfills two basic requirements: One is to charge the battery so that you crank and start the car each and every time you need to.

The other is to provide the electrical current for everything that requires it (think radio, blower motor, headlights, etc.), as you're driving down the road.

So, when the alternator fails, you'll notice one or several of the following symptoms:

1. The charge light (also known as the battery light) will be shining nice and bright on your Civic's instrument cluster.
2. Whenever you turn on the headlights (night driving), they glow very dim.
3. The car won't crank. It will only crank and start if you jump start your Civic.
4. The only way the car cranks and starts is if you charge the battery.
5. The idle may get high when you come to a stop.
6. The A/C will initially work and then the PCM commands it to de-activate (making you think you've got A/C compressor problems).

TEST 1: Battery Voltage Test With Engine Running

The very first thing you'll do is to see what the battery's voltage is with your Civic's engine running (with a multimeter in Volts DC mode of course).

If the alternator is defective and NOT charging the battery, your multimeter will register a battery voltage of 12.5 Volts or less.

If your Civic's alternator is working (and thus charging), your multimeter will show a voltage of 13.5 to 14.5 Volts DC.

Now, if the battery is completely dead on your Civic, you'll need to charge it up enough so that the car can idle for about 5 to 10 minutes (while you perform the test).

These are the test steps:

1. 1

   Crank and start your Honda Civic and select Volts DC mode on your multimeter.

2. 2

   Probe the positive battery terminal with the red multimeter test lead.
   
   With the black multimeter test lead, probe the negative battery terminal on your Honda Civic's battery.

3. 3

   Your multimeter is gonna' register one of two possible readings and they are:
   
   1.) A steady 13.5 to 14.5 Volts DC.
   
   2.) Or 12.5 Volts that will decrease the longer the engine stays running.

4. 4

   Put an electrical load on the alternator to further confirm that it's either charging or not charging.
   
   You can do this by turning on every accessory possible (inside the vehicle). For example: Turn on the A/C or heater on high, turn on the windshield wipers, turn on the headlights, turn on everything and anything that uses electricity inside and outside of the vehicle.

5. 5

   Your multimeter will show you one of two things (as you turn on all of this stuff):
   
   1.) The multimeter will register a nice and steady 13.5 to 14.5 Volts DC no matter what gets turned on.
   
   2.) It will register 12.5 V DC and this voltage will decrease more and more as you turn on stuff inside your Honda vehicle.

OK, let's interpret your multimeter test results:

CASE 1: Your multimeter registered 13.5 to 14.5 Volts. This voltage test result tells you that the alternator is working (charging the battery).

No further testing is required, since this multimeter test result eliminates the alternator on your Honda Civic as bad.

Now, if you're having to jump-start the car to get it going, this test result points to a bad battery or a parasitic drain. A parasitic drain is tech-speak for something staying on (usually inside the car, for example: a dome-light) and draining the battery while the engine is off.

CASE 2: Your multimeter registered a voltage that steadily dropped down to 9 Volts. This is a clear indication that your Honda Civic's alternator IS NOT charging the battery.

Replacing the alternator at this point usually solves around 90% of the No Charge conditions on any 1.7L 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: TEST 2: Checking The Continuity Of The Bat (+) Cable.