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

TEST 2: Checking The Continuity Of The Bat (+) Cable

You're probably already aware that your Honda Civic's alternator has two electrical connections.

One of them is a heavy gauge wire that connects to the battery's positive (+) post across an 80 amp mega fuse (located on the under-hood fuse box).

All of the electrical power that the alternator produces, to charge the battery and to power any of your Honda Civic's electrical needs, passes across this 80 A mega fuse and sometimes this mega fuse gets blown.

So in this test step, you're going to verify that this fuse is OK on your 1.7L Honda Civic before we proceed with the next (and last test)... which is checking the alternator fuse in the under-dash fuse/relay box (inside your Civic).

NOTE: This 80 amp mega-fuse is labeled with the number 19 in image 2 of 2 in the image viewer.

This is what you'll need to do:

1. 1

   Disconnect the battery negative (-) cable terminal from the battery negative post. The positive cable remains connected.
   
   IMPORTANT: Don't continue to the next step without first disconnecting the negative cable from the negative battery post.

2. 2

   After disconnecting the battery negative (-) cable, turn on your multimeter and select Ohms mode.

3. 3

   Your Honda Civic's alternator has only one big wire attached to it. This wire is attached with a nut. So, place your multimeter's RED test lead on the stud to which this wire is connected to.
   
   The arrow in the photo points to this stud.

4. 4

   With the black multimeter test lead, probe the center of the battery positive post on your Honda Civic's battery.

5. 5

   You'll get one of two results.
   
   1.) If the 80 Amp mega fuse, protecting this circuit, is blown, your multimeter will indicate a reading of OL (which means over limit). In other words, there will be NO continuity.
   
   2.) If the 80 amp mega fuse is OK and not blown, your multimeter will register an Ohms reading of 0.5 Ohms or less. In other words, there will be continuity.

Let's take a look at what your results mean:

CASE 1: Your multimeter registered continuity. This is good, since it indicates that the 80 amp mega-fuse protecting this circuit is OK and not blown.

The last test to do also involves checking the condition of another fuse. Except that this is just a regular plastic blade type fuse found in the fuse box under the dash. For this test, go to: TEST 3: Checking The Alternator Fuse.

CASE 2: Your multimeter DID NOT register continuity. This result tells you that the 80 amp mega fuse is blown and this will keep the alternator from charging the battery.

This fuse is locate in the under-hood fuse box and is labeled with the number 19 in image 2 of 2 in the image viewer above.

Replace the fuse and retest. Replacing the 80 amp mega fuse (if it's blown) should solve your No Charge condition. You'll have to investigate the reason this mega fuse blew, since they don't get blown for no particular reason.

TEST 3: Checking The Alternator Fuse

So far, you have checked and verified that: One, the battery's voltage (with the engine running) is at or below 12.5 Volts.

Two, the 80 amp mega-fuse, in the under-hood fuse box, is not blown.

The next step (and the last one), before concluding the alternator is fried, is to check the alternator fuse that's located in the under-dash fuse box.

This fuse is the one labeled with the number 4 in the illustration in the image viewer and is a 10 amp fuse.

NOTE: You can enlarge the image in the image viewer to get a good view of the location of the number 4 fuse.

This is what you need to do:

1. 1

   Reconnect the battery to its battery negative (-) cable, that you disconnected in the previous test.

2. 2

   Locate the alternator fuse, which will be located in the under-dash fuse/relay box inside your Honda Civic.
   
   The alternator fuse of the under-dash fuse/relay box is the number 4 fuse.

3. 3

   Once you have located the alternator fuse, remove it and check that it's not blown.

4. 4

   If it is blown, replace it with a new one and repeat TEST 1.

Let's analyze your test results:

CASE 1: The alternator fuse is NOT blown. This is good and let's you know that the alternator has all of the power sources it needs to charge, since it isn't, this result also let's you know that the alternator is bad and needs to be replaced.

CASE 2: The alternator fuse IS blown. Replace the fuse with another of the same amperage rating (10 amps) and start the car and check to see if the alternator is now charging the battery by repeating TEST 1.