How To Test The MAP Sensor (2006-2007 3.9L Chevrolet Malibu)

TEST 2: Verifying MAP Sensor Has 5 Volts And Ground

For the most part when the manifold absolute pressure (MAP) sensor does not produce a decreasing/increasing voltage signal as you apply/release vacuum to it, it usually means that the MAP sensor is defective.

But there are times that this result is due to the MAP sensor not receiving 5 Volts or Ground from the fuel injection computer.

So in this test section we're going to do a simple multimeter voltage test on the wires that feed the MAP sensor with 5 Volts and Ground.

If the MAP sensor is getting 5 Volts and Ground then you can conclude that it is defective (if it didn't pass TEST 1).

IMPORTANT: Be careful not to connect the Ground wire to 12 Volts (battery power) or you will fry the fuel injection computer on your 3.9L V6 Chevy Malibu or Impala. The multimeter voltage test indicated in the test steps below is one of the safest way to test this Ground.

These are the test steps:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Turn the key the ON position but don't start the engine.

3. 3

   Verify that the GRY wire has voltage (4.5 to 5 Volts DC) with the key on but engine off.
   
   Connect the red multimeter test lead (using the appropriate tool) to the GRY wire.
   
   Connect the black multimeter test lead to the negative battery terminal.
   
   Your multimeter should read 4.5 to 5 Volts DC.

4. 4

   Verify that the ORG/BLK wire has Ground with the key on but engine off.
   
   Connect the black multimeter test lead (using the appropriate tool) to the ORG/BLK wire.
   
   Connect the red multimeter test lead to the positive battery terminal.
   
   Your multimeter should read 12 Volts DC.

These are what the test results mean:

CASE 1: The MAP sensor is being fed 5 Volts and Ground. This is the correct and expected test result.

You can conclude that the manifold absolute pressure (MAP) sensor is defective only if you have:

• Confirmed that the MAP signal voltage does not decrease/increase as you apply/release vacuum to the MAP sensor.
• Confirmed that the MAP sensor is getting 5 Volts and Ground.

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CASE 2: Multimeter confirms that the MAP sensor IS NOT getting 5 Volts. Without 5 Volts the MAP sensor on your 3.9L Chevy Malibu or Impala will not function.

The most likely cause of this missing voltage is an open-circuit problem in the 5 Volts wire between the MAP sensor connector and the fuel injection computer's connector.

CASE 3: Multimeter confirms that the MAP sensor IS NOT getting Ground. Without Ground the MAP sensor on your 3.9L Chevy Malibu or Impala will not function.

The most likely cause of this missing Ground is an open-circuit problem in the Ground wire between the MAP sensor connector and the fuel injection computer's connector.

More GM 3.9L Test Tutorials

If this tutorial was helpful, be sure and take a look at all of the 3.9L Chevrolet Malibu and Impala test tutorials in this index: GM 3.9L Index Of Articles.

Here's a sample of the tutorials you'll find there:

• How To Test The Engine Compression (2006-2010 3.9L V6 Engine).
• How Often Should I Replace The Spark Plugs (2006-2010 3.9L V6 Engine).
• How To Test A Blown Head Gasket (2006-2010 3.9L V6 Engine).
• Ignition System Wiring Diagram (2006-2007 3.9L Chevrolet Malibu).