How To Test The Alternator (2002-2005 2.2L Ecotec)

TEST 2: Checking The Alternator's Battery Circuit Inline Fuse

The alternator's output reaches the battery across the wire that's connected to the alternator's stud (via a nut). The stud that I'm referring to is the one that the red multimeter test lead is connected to in the illustration above.

This battery wire (that connects to this stud) has an inline fusible link and it sometimes gets blown. When this happens, the alternator's output won't reach the battery (and make you believe that the alternator is bad).

So, in this test, we're gonna' do a simple multimeter resistance test to see if it's OK or if it's blown.

NOTE: The battery negative (-) terminal must be disconnected from the battery before you begin this test.

These are the test steps:

1. 1

   Disconnect the battery negative (-) terminal and set your multimeter to Ohms mode. Don't proceed to the next step without first disconnecting the battery from its negative cable.

2. 2

   Connect the red multimeter test lead to the stud on the rear of the alternator. Connect the black multimeter test lead to the battery positive cable. See the illustration above.

3. 3

   If the fusible link is OK, your multimeter should read continuity. If the fusible link is blown, your multimeter will show a reading of OL.

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

CASE 1: The fusible link is NOT blown. This is the correct and expected test result.

If your car is a Chevrolet Cavalier or a Classic, then you can consider the alternator as bad only if your test result in TEST 1 indicated a battery voltage of 12.5 or less with the engine running. You do not have to go to TEST 3 since the alternator, on these vehicles, does not have a GEN BATT fuse (for the alternator).

If your car is an Oldsmobile Alero or a Pontiac Grand Am or a Pontiac Sunfire, your next step is to check the GEN BATT fuse in the under-hood fuse box. For this test, go to: TEST 3: Checking The GEN BATT Fuse.

CASE 2: The fusible link is blown. This test result tells you that the alternator's charge is NOT reaching the battery.

Replacing the fusible link should solve your No Charge condition. You'll have to investigate the reason this fusible link blew, since they don't get blown for no particular reason.

In case you're wondering, this fusible link is usually located on the starter motor's solenoid.

TEST 3: Checking The Alternator's GEN BATT Fuse

NOTE: This section applies on to the 2002-2004 2.2L Oldsmobile Alero, 2002-2005 2.2L Grand Am, and the 2002-2005 2.2L Sunfire. The Chevy Cavalier and Classic covered by this tutorial do not use a GEN BATT fuse.

In this last test, we are going to make sure that the GEN BATT fuse is not blown. If this fuse is blown, the alternator will not charge the battery.

Now, in case you're wondering where this fuse is located: it's usually located in the fuse and relay box under the hood.

In the vehicles covered by this tutorial, the GEN BATT fuse is a 10 Amp fuse.

This is what you need to do:

1. 1

   Locate the 10 amp GEN BATT fuse, which will be located in the under-hood fuse box inside your 2.2L Ecotec equipped GM car.

2. 2

   Once you have located the 10 amp GEN BATT fuse, remove it and check that it's not blown.

3. 3

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

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

CASE 1: The GEN BATT 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 GEN BATT 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.

Where To Buy The Alternator And Save

Check out the links below and shop/compare for the alternator:

Not sure if the above alternator and alternator belt fit you particular 2.2L Ecotec equipped vehicle (2002-2005 2.2L Ecotec Chevrolet Cavalier and Classic; Oldsmobile Alero; Pontiac: Grand Am and Sunfire)? Don't worry, once you get to the site, they'll make sure the parts fit and if they don't they'll ask you about your vehicle's specifics to find you the right parts.