MAF TEST 1: Testing The Power Circuit

Making Sure The MAF Sensor Is Getting Power. How To Test The GM MAF Sensor (3.1L, 3.4L, 4.3L, 5.0L and 5.7L)

The very first thing that we'll do, to get our MAF sensor diagnostic on the way, is check that the MAF sensor is receiving 12 volts.

The procedure I recommend for you to use (to accomplish all of the tests below) is to use a test probe that pierces thru' the wire's insulation (to see what this tool looks like: Wire Piercing Probe).

It's best NOT to insert anything into the MAF sensor connector's female terminals... or you could damage them (this would require that you replace the MAF sensor connector).

Whatever method you use, the key here is not to damage the female terminal or the wire. Again, be careful. Use common sense and take all necessary safety precautions.

OK, these are the test steps:

  1. 1

    Place your multimeter's dial in VOLTS DC mode.

  2. 2

    Do not disconnect MAF sensor connector from the MAF sensor.

  3. 3

    With the RED multimeter test lead and an appropriate tool, probe the MAF sensor connector's C circuit as shown in the photo.

  4. 4

    With the BLACK lead of the multimeter probe BATT (-) negative terminal.

  5. 5

    Turn Key On with the engine Off. You should see 12 Volts on the multimeter. Do you have 12 volts?

Let's take a look at your test results:

CASE 1: Your multimeter registered 12 Volts: This is the correct result and tells you that the MAF sensor is getting power.

Your next step is to make sure the MAF sensor has ground, for this next test go to: MAF TEST 2: Testing The Ground Circuit.

CASE 2: Your multimeter DID NOT register 12 Volts: Recheck all of your multimeter connections and retest.

If you still do not see these 12 Volts on your multimeter... then this exonerates the MAF sensor as BAD, since without this voltage.. it's not gonna' work.

Your next step is to repair/restore this power circuit. Once this power circuit has been restored to the MAF sensor... it should start working again.

MAF TEST 2: Testing The Ground Circuit

Making Sure The MAF Sensor Is Getting Ground. How To Test The GM MAF Sensor (3.1L, 3.4L, 4.3L, 5.0L and 5.7L)

So far, in your testing of the MAF sensor, you've confirmed that the it's getting power (TEST 1).

The next test step is to make sure the MAF sensor is getting a good ground (since without ground it won't work).

Like the previous voltage test you just performed... this a very easy multimeter test too.

Alright, this is what you need to do:

  1. 1

    Place your multimeter in Volts DC mode.

  2. 2

    With the BLACK multimeter test lead and an appropriate tool, probe the wire labeled with the letter B in the photo in the image viewer.

  3. 3

    Connect the RED multimeter lead to the battery positive (+) Terminal.

  4. 4

    You should see 12 Volts on the multimeter. Do you have 12 volts?

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

CASE 1: Your multimeter registered 12 Volts: This result confirms that the MAF sensor is getting a good ground.

Your next step is to make sure the MAF sensor is producing a good MAF Hertz Frequency signal, for this, go to MAF TEST 3: Testing The MAF Signal.

CASE 2: Your multimeter DID NOT register 12 Volts: Recheck all of your multimeter connections and retest.

If you still do not see these 12 Volts... then this exonerates the MAF sensor as BAD, since without a good path to ground.. it's not gonna' work.

Your next step is to repair/restore this ground circuit. Once this ground circuit has been restored to the MAF sensor... it should start working again.