The alternator test is probably one of the most straightforward tests you can perform on your 2.2L Buick Century or 2.2L Oldsmobile Cutlass Ciera.
You don't need fancy diagnostic equipment since you can test the alternator with a simple multimeter.
In this tutorial, I'll explain how step by step. With your test results, you'll easily and quickly find out if the alternator is fried or not.
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar El Alternador (1993-1996 2.2L Buick Century, Oldsmobile Cutlass Ciera) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicles:
- 2.2L Buick Century: 1993, 1994, 1995, 1996.
- 2.2L Oldsmobile Cutlass Ciera: 1993, 1994, 1995.
- 2.2L Oldsmobile Ciera: 1996.
Important Testing Tips
The following tips will help you accomplish the tests in this tutorial:
TIP 1: Before you start the alternator tests, make sure the battery is fully charged (since you'll have to crank and start the engine to test the alternator).
TIP 2: You can use a digital multimeter or an analog multimeter.
TIP 3: Take all necessary safety precautions. Be alert and think safety all of the time since you'll be working around a running engine.
Symptoms Of A Bad Alternator
The alternator is the component that charges the battery after the engine has started.
It also provides the voltage and amperage that the electrical accessories in your car need to run.
If the alternator fails, it stops charging the battery, and the car will run until it discharges.
When the alternator fails, you're going to see one or more of the following symptoms:
- The charge light (also known as the battery light) will be shining nice and bright on your vehicle's instrument cluster.
- Whenever you turn on the headlights (night driving), they glow very dim.
- The car won't crank. It will only crank and start if you jump start your vehicle.
- The only way the car cranks and starts is if you charge the battery.
TEST 1: Checking Alternator Voltage Output With A Multimeter
For our first test, we'll check the battery's voltage with the engine running.
This battery voltage test will let us know immediately if the alternator is charging the battery.
To confirm the alternator is okay, the battery voltage that we need to see is a voltage between 13 to 14.5 Volts DC.
If the battery voltage is 12.5 Volts or less, the alternator is not charging the battery, and we'll move on to the next test.
These are the test steps:
Start the engine and let it idle.
Place your multimeter in Volts DC mode.
Check the battery's voltage with your multimeter.
The multimeter should register 13.5 to 14.5 Volts.
If it doesn't, don't worry about this just yet, continue to the next step.
Turn on every accessory possible while observing the multimeter. Like the headlights, the A/C or heater (high blower speed), the windshield wipers, the radio, the rear window defroster, etc.
As each accessory comes on, they'll place a load on the charging system (alternator).
As each accessory comes on, your multimeter will do one of two things:
1.) The multimeter's voltage reading will decrease slightly and then stabilize around 13.5 to 14.5 Volts DC (when something comes on).
2.) The DC voltage reading will decrease to 10 Volts DC.
Let's analyze your multimeter test results:
CASE 1: The multimeter maintained a 13.5 to 14.5 Volts value thru' out the whole test. This test result confirms the alternator is functioning correctly.
Since the alternator is charging the battery, no further testing is required.
CASE 2: The multimeter DID NOT maintain a 13.5 to 14.5 Volts value. This test result confirms the alternator is not charging the battery.
The next step is to test the continuity of the wire connecting the alternator to the battery. For this test go to: TEST 2: Testing The Continuity Of The Alternator's Output Wire.
TEST 2: Testing The Continuity Of The Alternator's Output Wire
The alternator's amperage and voltage output are delivered to the battery by the battery cable that connects to the rear of the alternator.
This battery cable connects to a stud on the rear of the alternator. I've labeled the stud with the orange arrow with the '+' symbol in the image above.
An inline fusible link protects the cable (that connects to this stud), and in some cases, this fusible link will get blown.
We can check the inline fusible link is OK by doing a simple multimeter continuity test on the cable.
If the cable has continuity between the battery positive (+) post and the alternator, the inline fusible link is OK, and we'll move on to TEST 3.
OK, let's get started:
Disconnect the battery negative (-) cable from the battery but leave the positive (+) cable connected to the positive (+) post.
IMPORTANT: Do not proceed to the next steps until you do this first.
Set your multimeter to Ohms mode.
Connect the red multimeter test lead to the stud shown in the photo above.
The alternator's output wire connects to the stud the arrow points to (in the photo above).
Connect the black multimeter test lead on the battery positive (+) terminal (at the battery).
The battery negative (-) wire must remain disconnected from the battery.
Your multimeter will register one of two values:
1.) Continuity (usually an Ohms value of about 0.5 Ohms).
2.) No continuity (an infinite Ohms reading (OL)).
OK, let's interpret your test results:
CASE 1: Your multimeter registered continuity (usually 0.5 Ohms). This is the correct and expected test result and it tells you the inline fusible link protecting the alternator's output wire is OK.
So far, it's looking like the alternator is bad. There's still one more test to do, go to: TEST 3: Making Sure The ALT Fuse Is Not Blown.
CASE 2: Your multimeter DID NOT register continuity, it registered OL. This test result confirms the inline fusible link protecting this wire is blown.
Your next step is to replace the inline fusible link and retest.