TEST 1: Testing The Power Circuit For 12 Volts

Testing The MAF Sensor Power Circuit (1997, 1998 3.0L Mitsubishi Montero)

To get the MAF sensor diagnostic under way, we'll start by checking and confirming that the MAF sensor is getting power.

This power is in the form of battery voltage (12 Volts) and comes from the Multiport Fuel Injection Relay in the engine compartment relay box.

These are the test steps:

  1. 1

    Place the multimeter in Volts DC mode.

  2. 2

    Connect the red multimeter test lead to the wire that connects to the connector terminal identified with the number 4 (see the illustration above) using an appropriate tool.

  3. 3

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

  4. 4

    Turn the key ON but don't crank or start the engine.

  5. 5

    The multimeter should register between 10 to 12 Volts DC.

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

CASE 1: The multimeter registered 10 to 12 Volts DC. This is the correct test result and confirms that the MAF sensor is getting juice (12 Volts).

The next step is to verify that it's also getting a good Ground, go to: TEST 2: Testing The Ground Circuit.

CASE 2: The multimeter DID NOT register 10 to 12 Volts DC. Your next step is to find out why this voltage is missing since without power, the MAF sensor won't work. Repairing the cause of the missing voltage will solve the MAF sensor issue/problem lighting up the check engine light on your Mitsubishi Montero.

TEST 2: Testing The Ground Circuit

Testing The MAF Sensor Ground Circuit for 12 Volts (1997, 1998 3.0L Mitsubishi Montero)

In this test step, we're gonna' make sure that your 3.0L V6 Mitsubishi Montero's PCM is feeding the MAF sensor with Ground, since without this Ground the sensor won't work.

The wire that feeds the MAF sensor this Ground is the wire that connects to terminal #5 of the MAF sensor connector. As in TEST 1, we'll use the multimeter to check this circuit.

IMPORTANT: Be careful and do not short this circuit to battery voltage accidentally or intentionally or you'll fry the PCM. Using a digital multimeter to check this circuit is the safest way to check for Ground.

These are the steps:

  1. 1

    Place the multimeter in Volts DC mode.

  2. 2

    Connect the black multimeter test lead to the wire that connects to the connector terminal identified with the number 5 (see the illustration above) using an appropriate tool.

  3. 3

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

  4. 4

    Turn the key ON but don't crank or start the engine.

  5. 5

    The multimeter should register between 10 to 12 Volts DC.

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

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

The next test is to verify that the MAF sensor is creating a good MAF signal based on the airflow the engine is breathing. For this test go to: TEST 3: Testing The MAF Signal Circuit.

CASE 2: The multimeter DID NOT register 10 to 12 Volts DC. This exonerates the MAF sensor as being bad, since without Ground, the MAF sensor will not work and this will light up the check engine light (CEL) on your instrument cluster.

Repairing the cause of the missing Ground will solve the problem with the MAF sensor.