CTS 2006-2007, CTS-V 2005-2007, DTS 2006-2007

Manifold Absolute Pressure Sensor

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Operation



The Manifold Absolute Pressure (MAP) sensor measures the pressure inside the intake manifold. Pressure in the intake manifold is affected by engine speed, throttle opening, air temperature, and Barometric Pressure (BARO). A diaphragm within the MAP sensor is displaced by the pressure changes that occur from the varying load and operating conditions of the engine. The sensor translates this action into electrical resistance. The MAP sensor wiring includes 3 circuits. The Engine Control Module (ECM) supplies a regulated 5 volts to the sensor on a 5-volt reference circuit. The ECM supplies a ground on a low reference circuit. The MAP sensor provides a signal voltage to the ECM, relative to the pressure changes, on the MAP sensor signal circuit. The ECM converts the signal voltage input to a pressure value.

Under normal operation the highest pressure that can exist in the intake manifold is equal to BARO. This occurs when the vehicle is operated at Wide-Open Throttle (WOT) or when the ignition is ON while the engine is OFF. Under these conditions, the ECM uses the MAP sensor to determine the current BARO. The lowest manifold pressures occur when the vehicle is idling or decelerating. MAP can range from 10 kPa, when pressures are low, to as much as 103 kPa when pressures are high, depending on the BARO. The ECM monitors the MAP sensor signal for pressure outside of the normal range.

Removal & Installation



4.6L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the fuel injector sight shield, if necessary.
  4.  
  5. Disconnect the engine harness electrical connector from the Manifold Absolute Pressure (MAP) sensor.
  6.  
  7. Remove the MAP sensor bracket bolt.
  8.  
  9. Remove the MAP sensor bracket.
  10.  
  11. Remove the MAP sensor.
  12.  

To install:

  1. Install the MAP sensor.
  2.  
  3. Install the MAP sensor bracket.
  4.  
  5. Install the MAP sensor bracket bolt.
  6.  
  7. Tighten the bolt to 89 inch lbs. (10 Nm).
  8.  
  9. Connect the engine harness electrical connector to the MAP sensor.
  10.  
  11. Install the fuel injector sight shield, if necessary.
  12.  

5.7L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the fuel injector sight shield.
  4.  
  5. Disconnect the MAP sensor electrical connector.
  6.  
  7. Pull the MAP sensor forward in order to release the sensor from the retainer.
  8.  
  9. Lift the MAP sensor upward and remove.
  10.  

To install:

  1. Lightly coat the MAP sensor seal with clean engine oil before installing the sensor.
  2.  
  3. Install the MAP sensor. Push down the sensor in order to engage the retainer.
  4.  
  5. Connect the MAP sensor harness connector.
  6.  
  7. Install the fuel injector sight shield.
  8.  

6.0L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the engine sight shield.
  4.  
  5. Disconnect the MAP sensor electrical connector.
  6.  
  7. Pull the MAP sensor (714) forward in order to release the sensor from the retainer.
  8.  
  9. Lift the MAP sensor upward.
  10.  
  11. Remove the MAP sensor seal (715) if necessary.

    Click image to see an enlarged view

    Fig. Manifold Absolute Pressure (MAP) Sensor removal 6.0L

  12.  

To install:

  1. Lightly coat the MAP sensor seal with clean engine oil before installing the sensor.
  2.  
  3. Install the MAP sensor (714). Push down the sensor in order to engage the retainer.
  4.  
  5. Connect the MAP sensor harness connector.
  6.  
  7. Install the engine sight shield.
  8.  

Testing



  1. Ignition OFF, remove the vacuum source from the MAP sensor.
  2.  
  3. Ignition ON, observe and record the scan tool MAP sensor pressure parameter. This is the first MAP sensor reading.
  4.  
  5. With the J 23738-A or equivalent vacuum tester, apply 5 in Hg (17 kPa) of vacuum to the MAP sensor. Observe and record the scan tool MAP sensor pressure parameter. This is the second MAP sensor reading.
  6.  
  7. Subtract the second MAP sensor reading from the first MAP sensor reading. Verify that the vacuum decrease is within 1 in Hg (4 kPa) of the applied vacuum.
  8.  
  9. If the vacuum decrease is not within the specified range, replace the MAP sensor.
  10.  
  11. With the J 23738-A or equivalent vacuum tester, apply 10 in Hg (34 kPa) of vacuum to the MAP sensor. Observe and record the scan tool MAP sensor pressure parameter. This is the third MAP sensor reading.
  12.  
  13. Subtract the third MAP sensor reading from the first MAP sensor reading. Verify that the vacuum decrease is within 1 in Hg (4 kPa) of the applied vacuum.
  14.  
  15. If the vacuum decrease is not within the specified range, replace the MAP sensor.
  16.  

 
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