TEST 1: Making Sure The MAF Sensor Is Getting 12 Volts
The first thing that we're going to do is make sure that the MAF sensor is getting 10 to 12 Volts DC.
The wire that delivers this voltage to the MAF sensor is the pink (PNK) wire of its 3-wire connector.
In the photo above, I've labeled the PNK wire with the letter C.
IMPORTANT: If you probe the front of the female terminal (of the connector), be careful not to damage it, or you'll need to replace the connector with a new one.
These are the test steps:
- 1
Put the multimeter in Volts DC mode.
- 2
Disconnect the MAF sensor from its electrical connector.
- 3
With the red multimeter test lead and an appropriate tool, probe the wire labeled with the letter C.
CAUTION: If you probe the front of the female terminal, be careful not to damage it with the multimeter test lead. - 4
Connect the black multimeter test lead to the battery negative (-) terminal.
- 5
Turn key to the ON position but don't crank or start the engine.
- 6
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 receiving power.
The next step is to make sure that the MAF sensor is getting Ground. For this test go to: TEST 2: Making Sure The MAF Sensor Is Getting Ground.
CASE 2: The multimeter DID NOT register 10 to 12 Volts. This test result lets you know that the mass airflow sensor isn't getting power. Without power, it will not function.
Your next step is to find out why this voltage is missing and resolve the problem.
Once you've restored power to the wire, your MAF sensor should function again.
TEST 2: Making Sure The MAF Sensor Is Getting Ground
So far, your TEST 1 result indicates that the mass airflow sensor is receiving the power it needs.
In this test section, we're going to make sure that it's receiving Ground.
The wire that delivers Ground to the mass airflow sensor is labeled with the letter B in the photo above.
This wire is either black (BLK) or black with a white stripe (BLK/WHT).
IMPORTANT: The Ground provided to the mass airflow sensor is a chassis Ground. Be careful and don't pass battery 12 Volts to this wire, or you'll end up causing a short-circuit problem. The multimeter voltage test I'm recommending in the instructions below is a safe way to check for the presence of Ground in this wire.
Let's get testing:
- 1
Put the multimeter in Volts DC mode.
- 2
Disconnect the MAF sensor from its electrical connector.
- 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
Connect the red multimeter test lead to the battery positive (+) terminal.
- 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 lets you know that the MAF sensor is getting Ground.
For our last test, we need to make sure that the MAF sensor is producing a Hertz frequency signal that increases/decreases as you accelerate/decelerate the engine. For this test go to: TEST 3: Testing The MAF Signal With A Multimeter.
CASE 2: The multimeter DID NOT register 10 to 12 Volts. This test result tells you that the MAF sensor is not receiving Ground. Without Ground, the MAF sensor will not function.
Your next step is to find out why this Ground is missing and resolve the problem.
Once you've restored Ground to the wire, your MAF sensor should function again.
TEST 3: Testing The MAF Signal With A Multimeter
Alright, if you've reached this section, you have:
- Confirmed that the MAF sensor is receiving 10 to 12 Volts (TEST 1).
- Confirmed that the MAF sensor is receiving Ground (TEST 2).
Now we're gonna' to check that the MAF sensor's output signal increases/decreases as you accelerate/decelerate the engine.
If the mass airflow sensor is bad, its output Hertz frequency signal will stay stuck in one value as you accelerate/decelerate the engine.
The wire that we're going to test, which carries the MAF sensor's signal, is the wire labeled with the letter A in the photo above.
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 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!
These are the test steps:
- 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
Put the multimeter in frequency (Hz) mode.
- 3
Connect the black multimeter lead to the battery negative (-) terminal.
- 4
Start the already warmed up engine.
- 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
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
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
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 lets you know that the MAF sensor is functioning 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 3.4L V6 Chevrolet, Pontiac Tutorials
You can find a complete list of 3.4L V6 Chevrolet (Pontiac) tutorials in this index:
Here's a small sample of the tutorials you'll find in the index:
- How To Test Engine Compression Test (3.4L V6 Chevrolet, Pontiac).
- How To Test A Blown Head Gasket (3.4L V6 Chevrolet, Pontiac).
- What Does The CKP Sensor Do? (3.4L V6 Chevrolet, Pontiac).
- How To Test The Throttle Position Sensor (3.4L V6 Chevrolet, Pontiac).
If this info saved the day, buy me a beer!
