Envoy, Rainer, Trailblazer 2006-2007

Manifold Absolute Pressure Sensor

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Operation



The Manifold Absolute Pressure (MAP) sensor checks for intake manifold pressure variations. Vacuum will vary according to the speed and load of the engine when everything is functioning normally. The engine's computer receives this manifold vacuum information from the MAP sensor, which then regulates fuel and spark accordingly.

Removal & Installation



4.2L Engine
  1. Disconnect the negative battery cable.
  2.  
  3. Turn OFF the ignition.
  4.  
  5. Disconnect the Manifold Absolute Pressure (MAP) sensor electrical connector.
  6.  
  7. Press the retainer locking tabs inward, then pull the retainer (1) up to remove it.
  8.  
  9. Remove the MAP sensor (2).
  10.  
  11. Inspect the MAP sensor seal for damage, and replace as necessary.

    Click image to see an enlarged view

    Fig. Location of the retainer (1) and the Manifold Absolute Pressure (MAP) sensor (2)-4.2L engine

  12.  

To install:

  1. Install the MAP sensor (2).
  2.  
  3. Install the MAP sensor retainer (1).
  4.  
  5. Connect the electrical connector.
  6.  
  7. Connect the negative battery cable.
  8.  

5.3L And 6.0L Engines
  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the manifold absolute pressure (MAP) sensor electrical connector (3).
  4.  
  5. Remove the MAP sensor retaining clip (2) from the intake manifold.
  6.  
  7. Remove the MAP sensor (1) from the intake manifold.

    Click image to see an enlarged view

    Fig. Location of the Manifold Absolute Pressure (MAP) sensor (1) and retaining clip (2)-5.3L and 6.0L engines

  8.  

To install:

  1. Lightly coat the MAP sensor seal with clean engine oil before installing the sensor.
  2.  
  3. Install the MAP sensor (1). Push the MAP sensor into the intake manifold.
  4.  
  5. Install the MAP sensor retainer (2) to the intake manifold.
  6.  
  7. Connect the MAP sensor electrical connector (3).
  8.  
  9. Connect the negative battery cable.
  10.  

Testing



  1. Disconnect the Manifold Absolute Pressure (MAP) sensor wiring harness.
  2.  
  3. Connect jumper wires between its terminals and wiring harness.
  4.  
  5. Turn the ignition to the ON position and take a voltage reading. Spec for this MAP is about 4.5-5.0 volts.
  6.  
  7. Run the engine and warm it up.
  8.  
  9. Take another voltage reading. It should differ from the non-running number and fluctuate when the engine is revved. If not, inspect the condition of the sensor seal for damage and replace if necessary.
  10.  
  11. If the sensor seal is okay, replace the MAP sensor.
  12.  

 
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