TEST 1: Testing The MAF's Power (12 V) Circuit
The very first thing we're gonna' do, is to make sure that the MAF sensor is getting power. This power comes in the form of 10 to 12 Volts DC when you turn on the Key.
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 (Wire Piercing Probe).
Whatever method you use, the key here is not to damage the female terminal or the wire... if you decide to probe the front of the MAF sensor's connector with your multimeter leads. Again, be careful. Use common sense and take all necessary safety precautions.
OK, let's get this show on the road:
Place your multimeter in VOLTS DC mode.
Probe the MAF sensor wire, that's identified with the letter A in the photo, with the red multimeter test lead.
This is the black with pink stripe (BLK/PNK) wire of the connector.
Connect the black multimeter test lead to the battery negative (-) terminal.
Turn Key on but don't crank or start the engine.
Your multimeter should display 10 to 12 Volts DC if battery power is present.
Let's interpret your test result:
CASE 1: Your multimeter registered 10 to 12 Volts. This tells you that the MAF sensor is getting power (10 to 12 Volts DC). The next step is to test the Ground circuit, go to TEST 2.
CASE 2: If your multimeter DID NOT register 10 to 12 Volts: recheck all of your multimeter connections and retest.
If your multimeter still doesn't register 10 to 12 Volts, then you've found the reason why the MAF sensor is not working (without power, it won't function). Restoring power to this wire will get the MAF back on its feet.
TEST 2: Testing The MAF's Ground Circuit
So far, you've verified that the MAF sensor on your Nissan Frontier (or Nissan Xterra) is getting juice (10 to 12 Volts DC).
Now you need to verify that it also has a good path to Ground. The circuit that provides this path to Ground is the wire labeled with the letter B.
IMPORTANT: Be careful when testing this wire (circuit), since this wire ends up connecting directly to the fuel injection computer. If you accidentally short it to battery power (12 Volts), you will fry the fuel injection computer.
OK, this is what you need do to:
Place your multimeter in VOLTS DC mode and disconnect the MAF sensor from its connector.
With the red multimeter test lead and an appropriate tool, probe the MAF sensor wire that is identified with the letter B in the photo.
This will be the green wire of the MAF sensor connector.
Connect red multimeter test lead to the battery positive (+) terminal.
Turn the Key to the On position but don't crank or start the engine.
Your multimeter should register 10 to 12 Volts if Ground is present in the wire.
Let's analyze your test result:
CASE 1: Your multimeter registered 10 to 12 Volts. This result indicates that your Nissan Frontier's (Nissan Xterra's) MAF sensor has a good Ground circuit. The next step is to test the MAF signal, go to: TEST 3: Testing The MAF Signal.
CASE 2: If your multimeter DID NOT register 10 to 12 Volts: recheck all of your multimeter connections and try the test again. If still no voltage, then this result exonerates the MAF sensor as the cause of the MAF code lighting up your check engine light (CEL) or MAF issue, since without this Ground, the MAF sensor will not produce a signal to the computer.
Finding and repairing the cause of this missing Ground will resolve the MAF sensor issue with your Nissan 2.4L Frontier Pick Up (or Nissan 2.4L Xterra).