How To Test The Isuzu 3.2L Manifold Absolute Pressure (MAP) Sensor

This tutorial will help you to diagnose a bad manifold absolute pressure (MAP) sensor (and DTC P0106, P0107, P0108, P01107) on your 3.2L 98-99 Isuzu Amigo, Rodeo, or Honda Passport.

All that you'll need, to successfully accomplish the three tests presented in this article is a multimeter. No scan tool is needed.

You can find this tutorial in Spanish here: Cómo Probar El Sensor MAP (1998-2004 3.2L V6 Isuzu Rodeo y Amigo) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to following vehicles, since they use the same MAP sensor:

  1. 3.2L V6 Isuzu Amigo: 1999, 2000.
  2. 3.2L V6 Isuzu Rodeo: 1998, 1999, 2000, 2001, 2002, 2003, 2004.
  3. 3.2L V6 Honda Passport: 1998, 1999, 2000, 2001, 2002.

Important Tips And Suggestions

TIP 1. All three wires coming out of the MAP sensor on your 3.2L Isuzu Amigo, Rodeo, or Honda Passport end up at the PCM (Powertrain Control Module = Fuel Injection Computer). So, be careful not to short these wires out when testing them.

TIP 2. If you don't have a vacuum pump, you can buy one online or you can rent one from your local auto parts store (AutoZone, O'Reilly Auto Parts, etc).

You can also use your mouth to apply vacuum to the MAP sensor.

TIP 3. You don't need to use a scan tool to test the MAP sensor. The testing instructions call for a multimeter. You can use a digital or an analog multimeter. Both will work.

Symptoms Of A Bad MAP Sensor

The fuel injection computer monitors the MAP signal, so when it fails, you'll definitely have the check engine light shining nice and bright with a MAP sensor trouble code.

You'll also see one or more of the following symptoms:

  1. MAP sensor diagnostic trouble codes:
    1. P0106. MAP/Barometric Pressure Circuit Performance.
    2. P0107. MAP/Barometric Pressure Circuit Low Input.
    3. P0108. MAP/Barometric Pressure Circuit High Input.
    4. P01106. MAP Sensor Circuit Intermittent Low Voltage.
    5. P01107. MAP Sensor Circuit Intermittent High Voltage.
  2. Really bad gas mileage.
  3. No power and/or hesitation as you accelerate the vehicle.
  4. Rough idle.
  5. Hard start (engine takes forever to start).
  6. Engine starts but stalls.
  7. Black smoke coming out of the tailpipe when the engine is running.

How Does The MAP Sensor Work?

How To Test The Isuzu 3.2L Manifold Absolute Pressure (MAP) Sensor

The manifold absolute pressure sensor's job is to measure the intake manifold's vacuum. In a nutshell, this is how the MAP sensor works:

  1. When you turn the Key to the On position and then start the engine, the MAP sensor gets power thru' the wire labeled with the letter C. This power is in the form of 5 Volts.
  2. Ground is provided to the MAP sensor by the fuel injection computer thru' the circuit labeled with the letter A.
  3. Now, as the engine idles, the pistons are creating vacuum inside the intake manifold (as they travel downwards in their stroke).
  4. So then, when you accelerate the engine, the pistons come up and down even faster which creates more vacuum which is immediately measured by the MAP sensor. This info is then sent to the fuel injection computer thru' the wire labeled with the letter B.
  5. So, no matter how much the engine revs up or decelerates, this will always cause a change in the intake manifold's vacuum and this vacuum changes are always relayed to the computer.
  6. The fuel injection computer uses this info (that the MAP sensor provides) to control fuel injection, ignition advance and a host of other things to keep your engine running smoothly.

TEST 1: Checking The MAP Signal

Checking The MAP Signal With A Multimeter. How To Test The Isuzu 3.2L Manifold Absolute Pressure (MAP) Sensor

The very first thing that you'll do, to get this show on the road, is to test the MAP signal that the MAP sensor creates.

What we'll do is connect a multimeter to the MAP signal wire and then apply vacuum to the MAP sensor.

On all of the 3.2L V6 Isuzu vehicles (and 3.2L V6 Honda Passport), the MAP signal wire is the red (RED) wire of the connector.

NOTE: The MAP sensor must remain connected to its electrical connector to test for the MAP signal voltage. You'll need to use a back probe or a wire-piercing probe to check for the MAP voltage signal in the wire. You can see an example of this tool here: Wire Piercing Probe.

OK, let's get testing:

  1. 1

    Remove the MAP sensor from the intake manifold. It may be necessary to unplug the sensor from its connector. If you do, be sure and reconnect it after removal.

  2. 2

    Connect your vacuum pump to the MAP sensor's vacuum inlet (using a vacuum hose).

  3. 3

    Set your multimeter's selector to Volts DC mode.

  4. 4

    Connect the red multimeter test lead, with the appropriate tool, to the wire labeled with the letter B (see the photo above).

    NOTE: The MAP sensor must be connected to its electrical connector to read the MAP voltage signal.

  5. 5

    Ground the black multimeter test lead directly on the battery negative (-) terminal.

  6. 6

    Power up the MAP sensor by turning the Key On (but Engine Off).

  7. 7

    The multimeter should read about 4.7 Volts DC without any vacuum being applied to the MAP sensor.

  8. 8

    Now, apply vacuum to the MAP sensor with the vacuum pump (or your mouth). You should see the voltage decrease as you apply vacuum:

    1.) 0 in. Hg = 4.7 Volts.

    2.) 5 in. Hg = 3.9 Volts.

    3.) 10 in. Hg = 3.0 Volts.

    4.) 20 in. Hg = 1.1 Volts.

    When you release the vacuum, the voltage should return to 4.7 Volts.

OK, let's take a look at what your vacuum pump test results mean:

CASE 1: Your multimeter registered the indicated voltages as you applied vacuum. This means that the manifold absolute pressure (MAP) sensor is good and not the cause of the MAP sensor code or problem on your Isuzu 3.2L Amigo, Rodeo, or Honda Passport. No further testing is required.

Now, if your vehicle still has a MAP sensor code lighting up the check engine light, take a look at the section: The MAP Sensor Code Won't Go Away for more info.

CASE 2: Your multimeter registered voltage, but it did not increase or decrease as you applied vacuum. Generally this test result tells you that the MAP sensor is bad.

Before you replace the MAP sensor, I suggest that you check that it's getting 5 Volts and Ground. If both are present, then you can conclude that the MAP sensor is bad. To test for power, go to: TEST 2: Checking The MAP Sensor's Power Circuit.

CASE 3: Your multimeter registered 0 Volts. Generally this test result tells you that the MAP sensor is bad.

Before you replace the MAP sensor, I suggest that you check that it's getting 5 Volts and Ground. If both are present, then you can conclude that the MAP sensor is bad. To test for power, go to: TEST 2: Checking The MAP Sensor's Power Circuit.