How To Test The MAF Sensor (1992-1993 3.3L V6 Pontiac Grand Am)

TEST 2: Making Sure The MAF Sensor Is Getting Ground

So far, the test result of TEST 1 indicates that your 3.3L V6 Pontiac Grand Am's MAF sensor is receiving 10 to 12 Volts.

In this test section, we're now going to make sure that the wire labeled with the letter B is supplying Ground to the MAF sensor.

On your specific vehicle, this wire may be a black with white stripe (BLK/WHT) wire or a black (BLK) wire.

To test for Ground in this wire, we're going to do a simple multimeter voltage test like the one we did in TEST 1 to check for power.

Let's get testing:

1. 1

   Put the multimeter in Volts DC mode.

2. 2

   Disconnect the MAF sensor from its electrical connector.

3. 3

   With the black multimeter test lead and an appropriate tool, probe the wire labeled with the letter B.
   
   CAUTION: If you probe the front of the female terminal, be careful not to damage it with the multimeter test lead.

4. 4

   Connect the red multimeter test lead to the battery positive (+) terminal.

5. 5

   You should see 10 to 12 Volts on the multimeter.

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

CASE 1: The multimeter registered 10 to 12 Volts. This is the correct and expected test result and it confirms that the MAF sensor is getting Ground.

Your next step is to test the MAF sensor's signal output. For this test go to: TEST 3: Testing The MAF Signal.

CASE 2: The multimeter DID NOT register 10 to 12 Volts. This test result tells you that the MAF sensor is not getting Ground. Without it, the sensor won't work.

Your next step is to find out why this Ground is missing and resolve the problem.

TEST 3: Testing The MAF Signal

So far your test results have indicated that:

• The MAF sensor is receiving 10 to 12 Volts.
• The MAF sensor is receiving Ground.

Now, for our last test, we're going to make sure that the MAF sensor is producing a Hertz frequency signal that increases/decreases as you accelerate/decelerate the engine.

If the MAF sensor is bad, its Hertz frequency signal will not increase/decrease as you accelerate/decelerate the engine. It will stay stuck in one single value.

Remember, you'll need a multimeter that can read Hertz frequency. If you don't have one, check out my recommendations here: Buying A Digital Multimeter For Automotive Diagnostic Testing.

IMPORTANT: The MAF sensor must remain connected to its electrical connector for this test to work. You'll need to use a wire piercing probe or a back probe (on the connector) to be able to read the Hertz signal that the MAF sensor is producing. You can see an example of this tool here: Wire Piercing Probe.

CAUTION: The engine has to be running to perform the MAF sensor's Hertz signal test. Take all necessary safety precautions. Think safety all of the time!

Let's get started:

1. 1

   With a suitable tool, connect to the red multimeter test lead to the wire labeled with the letter A as shown in the photo above.

2. 2

   Put the multimeter in frequency (Hz) mode.

3. 3

   Connect the black multimeter lead to the battery negative (-) terminal.

4. 4

   Start the already warmed up engine.

5. 5

   Note the Hertz reading on your multimeter as the engine idles.
   
   This reading may be stable (with only small fluctuations) or unstable with very extreme fluctuations.
   
   No matter what the instability in the reading, this will be your base reading.

6. 6

   Manually accelerate the engine from the engine compartment as you watch the multimeter's frequency readings.
   
   The Hertz frequency readings should increase as you accelerate the engine.

7. 7

   Let go of the throttle and let the engine return to idle.
   
   The Hertz reading should come down to the base Hertz reading you observed in step 5 of this test.

8. 8

   Repeat steps 6 and 7 several times.
   
   Your multimeter should register the Hertz reading increasing/decreasing as you accelerate/decelerate the engine.

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

CASE 1: The Hertz values increased/decreased as you accelerated/decelerated the engine. This is the correct and expected test result and it let's you know that the MAF sensor is working correctly.

CASE 2: The Hertz values DID NOT increase/decrease as you accelerated/decelerated the engine. The MAF sensor is bad and needs to be replaced.

More 3.3L Pontiac Grand Am Tutorials

You can find a complete list of 3.3L Pontiac Grand Am tutorials in this index:

• GM 3.3L Index Of Articles.

Here's a small sample of the tutorials you'll find in the index:

• How To Test Engine Compression Test (3.3L V6 Pontiac Grand Am).
• How To Test A Blown Head Gasket (3.3L V6 Pontiac Grand Am).
• How To Test The Throttle Position Sensor (3.3L V6 Pontiac Grand Am).
• What Does A MAF Sensor Do? (3.3L V6 Pontiac Grand Am).