TEST 1: Checking The MAF Sensor Power Circuit
The very first thing we'll do, to get our mass air flow (MAF) sensor diagnostic on the road, is to check that it's getting power.
In the next test (TEST 2), we'll check that the MAF sensor has a good Ground.
Power comes from a fuse and in the form of 10 to 12 Volts DC.
These you can check with a 12 Volt automotive test light or a multimeter. Although the test instructions below assume that you'll be using a multimeter.
OK, this what you'll need to do:
- Place the multimeter in Volts DC mode.
- Locate the wire identified with the letter C.
- This is the Pink wire.
- Connect the red multimeter test lead to this Pink wire using an appropriate tool.
- Connect the black multimeter test lead directly to the battery negative (-) terminal.
- Turn the key to the ON position (RUN position)
- Your multimeter should register 10 to 12 Volts DC.
- When done, turn the key Off and interpret your results below:
CASE 1: The multimeter recorded 10 to 12 Volts DC- So far so good, since this test result tells you that the mass air flow (MAF) sensor is getting power.
The next step is to make sure that the MAF sensor has a good Ground in the wire labeled with the letter B. For this test, go to: TEST 2: Checking The MAF Sensor Ground Circuit.
CASE 2: The Multimeter DID NOT record 10 to 12 Volts DC. Make sure that you're testing the correct wire, that your connections are OK, and repeat the test.
If you still don't see any voltage here, then you have found the reason why the MAF sensor is not working and the reason for the MAF sensor diagnostic trouble code (DTC).
Without power (10 to 12 Volts DC) in this wire, the MAF sensor won't work. Replacing the fuse and/or solving the issue causing this missing voltage will solve the MAF sensor issue on your 3.5L GM equipped vehicle.
TEST 2: Checking The MAF Sensor Ground Circuit
So far, you've confirmed that the mass air flow (MAF) sensor is getting power (10 to 12 Volts) in TEST 1.
The next step is to make sure that this power has a good Ground. This Ground is provided by the wire labeled with the letter B in the photo above.
You can check this Ground with a 12 Volt automotive test light or a multimeter. The test instructions below assume that you'll be using a multimeter.
OK, this is what you need to do:
- Place the multimeter in Volts DC mode.
- Locate the wire identified with the letter B.
- This is the Black with White stripe wire.
- Connect the black multimeter test lead to this Black with White stripe wire using an appropriate tool.
- Connect the red multimeter test lead directly on the battery positive (+) terminal.
- Your multimeter should immediately register 10 to 12 Volts DC.
Let's interpret your test results:
CASE 1: The multimeter recorded 10 to 12 Volts DC. This multimeter test result tells you that the MAF sensor on your pickup or car is getting a good Ground.
The next step is to make sure that the MAF sensor is working and outputting a MAF Signal on the wire labeled with the letter A. For this test, go to: TEST 3: Checking The MAF Sensor Signal.
CASE 2: The Multimeter DID NOT record 10 to 12 Volts DC. Make sure that you're testing the correct wire, that your connections are OK, and repeat the test.
If you still don't see any voltage here, then you now have confirmed that the MAF sensor isn't getting the Ground it needs to function. Repairing this Ground will get the MAF sensor back on its feet.
