Testing the MAP sensor is not difficult on the 2004, 2005, and 2006 3.5L V6 Chevy Malibu. The cool thing is that it can be accurately tested using only a multimeter and a vacuum pump.
In this tutorial, I'll explain how to test it and with the results of your test, you'll be able to find out if the MAP sensor is defective or not.
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar El Sensor MAP (2004-2006 3.5L Chevrolet Malibu) (at: autotecnico-online.com).
NOTE: You can find the MAP sensor test for the 2007-2008 3.5L Chevrolet Malibu here: How To Test The MAP Sensor (2007-2008 3.5L Malibu).
Symptoms Of A Bad MAP Sensor
Although your 3.5L Chevy Malibu comes equipped with a mass air flow sensor, it still uses a MAP sensor to measure the intake manifold pressure inside the intake manifold
Since it plays an important role in the engine management system, when it fails the check engine light is going to light up with a MAP sensor trouble code:
- P0107: Manifold absolute pressure (MAP) sensor circuit low voltage.
- P0108: Manifold absolute pressure (map) sensor circuit high voltage.
- P1106: Manifold absolute pressure (map) sensor circuit intermittent high voltage.
- P1107: Manifold absolute pressure (map) sensor circuit intermittent low voltage.
Besides a MAP sensor trouble code, you're going to see a few other symptoms. You might see one or more of the following:
- Extended cranking time. In other words the engine takes longer than usual to start.
- Black smoke coming out of the tailpipe.
- Once the engine starts, the engine idles rough and may even stall.
- The engine does not start.
- Lack of power when accelerating the engine under load.
- You're also going to experience bad gas mileage.
Let's get started with our first test.
MAP Sensor Wire Identification
Here is a brief description of the three wires of the manifold absolute pressure (MAP) sensor on the 2004, 2005, and 2006 3.5L Chevrolet Malibu:
Orange with black stripe (ORG/BLK) wire (A): This wire is the one that supplies Ground to the MAP sensor. This Ground is provided by your Chevy Malibu's fuel injection computer.
Light green (LT GRN) wire (B): This is the wire that transmits the MAP signal, that the sensor creates, to the fuel injection computer.
Gray (GRY) wire (C): This wire supplies the MAP sensor with power in the form of 5 Volts DC. This voltage is provided by your Chevy Malibu's fuel injection computer.
Where To Buy The MAP Sensor And Save
The following links will help you comparison shop for the MAP sensor:
Not sure if the MAP sensor will fit your particular GM vehicle? Don't worry, once you get to the site, they'll make sure it fits. If it doesn't, they'll find you the right one.
TEST 1: Testing The MAP Sensor's Voltage Signal
To test the MAP sensor we're going to remove it from its location on the intake manifold and attach a vacuum pump to it to check it's voltage signal.
By applying vacuum ourselves with a vacuum pump, we can get an accurate assessment of the MAP sensor's performance which will let us know if it's defective or not.
To better understand what it is that we're doing in this test I'm going to briefly describe how the MAP sensor works:
When you turn the key on but don't start the engine, the MAP sensor reports a voltage of about 4 to 4.5 Volts DC.
Now when the engine starts and vacuum is applied to the MAP sensor, it outputs a smaller voltage value.
If the MAP sensor is defective, it's voltage signal will stay stuck at a single value no matter how much vacuum is applied to it.
With this info under our belts, these are the test steps:
IMPORTANT: The MAP sensor must remain connected to its electrical connector for this test to work. To access the MAP signal inside the wire you'll need to use a back probe on the connector or a wire piercing probe on the wire. You can see an example of this tool here: Wire Piercing Probe Review (Power Probe PWPPPPP01).
- 1
Remove the MAP sensor from the intake manifold .
Reconnect the MAP sensor back to its electrical connector if you disconnected it to remove it. - 2
Place your multimeter in Volts DC mode.
- 3
With the red multimeter test lead probe the gray (GRY) wire of the MAP sensor connector.
- 4
Ground the black multimeter test lead directly on the battery negative (-) terminal.
- 5
Connect your vacuum pump to the MAP sensor's vacuum inlet nipple.
- 6
Turn the key on but don't crank or start the engine .
The MAP sensor voltage should be around 4.4 to 4.8 Volts without applying vacuum to the sensor. - 7
Apply vacuum to the MAP sensor with the vacuum pump.
The MAP sensor's voltage signal should decrease as you apply vacuum. - 8
Release the vacuum you applied to the MAP sensor with the vacuum pump.
The MAP sensor's voltage signal should increase back to the value you noticed in step 6.
Let's examine your test results:
CASE 1: The MAP voltage signal decreased as you applied vacuum and increased as you released vacuum. This is the correct test result and lets you know that the MAP sensor, on your 3.5 V6 Chevy Malibu, is functioning correctly.
CASE 2: The MAP sensor voltage signal did not decrease/increase as you applied/released vacuum. This test result tells you that the MAP sensor is defective and needs to be replaced.
CASE 3: Your multimeter registered 0 volt DC. This test result indicates one or two things: either the MAP sensor is defective or it's not getting power.
To further check this, we need to make sure that the MAP sensor is getting power. For this test go to: TEST 2: Making Sure The MAP Sensor Is Getting Power.
