How To Test The MAP Sensor (2005-2006 2.2L Chevrolet Cobalt)

TEST 2: Verifying MAP Sensor Has 5 Volts And Ground

In this test section, we're going to make sure that the MAP sensor is getting 5 Volts and Ground from the fuel injection computer.

Although it's rare for these 5 Volts and Ground to be missing, it's still a good idea to make sure that they are present. Especially because it only takes a very simple multimeter voltage test to find out.

The wire that feeds 5 Volts to the MAP sensor is the gray (GRY) wire labeled with the letter C in the photo above.

The wire that feeds Ground to the MAP sensor is the orange with black stripe (ORG/BLK) wire that's labeled with the letter A in the photo above.

IMPORTANT: You have to be very careful not to apply battery power (12 Volts DC) to the Ground wire of the MAP sensor's electrical connector. Applying battery power to the Ground wire of the connector will fry the fuel injection computer. The multimeter voltage test I'm recommending in the test instructions is a safe way to check for the presence of 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 multimeter confirms that the MAP sensor is being fed power and Ground. This is the correct and expected test result and lets you know that the fuel injection computer is providing power and Ground to the MAP sensor.

You can correctly conclude that the MAP sensor is defective and needs to be replaced only if you have:

• Confirmed that in TEST 1 the MAP sensor voltage signal did not decrease/increase as you applied/released vacuum to it.
• You have confirmed that it is getting 5 Volts DC and Ground.

If you need to replace the MAP sensor with a new one, check out my recommendations here: Where To Buy The MAP Sensor And Save.

CASE 2: Multimeter confirms that the MAP sensor IS NOT being fed power. The MAP sensor will not function if it doesn't receive 5 Volts from the fuel injection computer.

The most common cause of this missing voltage is an open-circuit problem in the wire that feeds this voltage to the MAP sensor.

CASE 3: Multimeter confirms that the MAP sensor IS NOT being fed Ground. The MAP sensor will not function if it doesn't receive Ground from the fuel injection computer.

The most common cause of this missing Ground is an open-circuit problem in the wire that feeds this Ground to the MAP sensor.

More GM 2.2L Test Tutorials

If this tutorial was helpful, be sure and take a look at all of the 2.2L Chevrolet Cobalt test tutorials in this index: GM 2.2L Index Of Articles.

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

• Electronic Throttle Body Tests (2005-2006 2.2L Chevrolet Cobalt).
• TAC System Wiring Diagram (2005-2009 2.2L Chevrolet Cobalt And Pontiac G5).
• APP Sensor Tests (2005-2010 2.2L Chevrolet Cobalt And Pontiac G6).