Montana SV6 (2006), Relay, Terraza, Uplander (2005-2007)

Manifold Absolute Pressure Sensor

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Operation



The Manifold Absolute Pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on the engine load. The MAP sensor has the following circuits:



5-volt reference circuit
 
Low reference circuit
 
MAP sensor signal circuit
 

The control module supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The control module also provides a ground on the low reference circuit. The MAP sensor provides a signal to the control module on the MAP sensor signal circuit which is relative to the pressure changes in the manifold. The control module should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The control module should detect a high signal voltage at a high MAP, such as the ignition is ON, with the engine OFF, or at a wide open throttle (WOT). The MAP sensor is also used in order to determine the barometric pressure (BARO). This occurs when the ignition switch is turned ON, with the engine OFF. The BARO reading may also be updated whenever the engine is operated at WOT. The control module monitors the MAP sensor signal for voltage outside of the normal range.

Removal & Installation



3.5L Engine
  1. Disconnect the Manifold Absolute Pressure (MAP) sensor electrical connector.
  2.  
  3. Remove the MAP sensor retraining bolt and bracket.
  4.  
  5. Remove the MAP sensor. Remove the MAP sensor port seal if it is still retained in the intake manifold.
  6.  

To install:

  1. Install the MAP sensor to the intake manifold.
  2.  
  3. Install the MAP sensor retaining bracket and tighten the bolt to 89 inch lbs. (10 Nm).
  4.  
  5. Connect the MAP sensor electrical connector.
  6.  

3.9L Engine
  1. Remove the intake manifold cover.

    Click image to see an enlarged view

    Fig. Disconnect the engine wiring harness (1) from the MAP sensor-3.9L engine

  2.  
  3. Disconnect the engine harness electrical connector from the Manifold Absolute Pressure (MAP) sensor.
  4.  
  5. Remove the MAP sensor bracket bolts and bracket.
  6.  
  7. Remove the MAP sensor from the intake manifold.
  8.  

To install:

  1. Inspect the MAP sensor seal for damage, and replace if necessary.
  2.  
  3. Install the MAP sensor.
  4.  
  5. Install the MAP sensor bracket and bolts and tighten to 18 ft. lbs. (25 Nm).
  6.  
  7. Connect the engine wiring harness to the MAP sensor.
  8.  
  9. Install the intake manifold cover.
  10.  

Testing



  1. Start the engine.
  2.  
  3. Monitor the DTC information with the scan tool.
  4.  
  5. If DTC P0641 or P0651 is also set then correct DTC P0641 or P0651 first.
  6.  
  7. Inspect for the following conditions:

    Disconnected, damaged, or incorrectly routed vacuum hoses
     
    MAP sensor disconnected from the vacuum source
     
    Restrictions in the MAP sensor vacuum source
     
    Intake manifold vacuum leaks
     
    Inspect for a properly functioning oxygen sensor--refer to Scan Tool Data List .
     

  8.  
  9. With the ignition ON, and the engine OFF, disconnect the MAP sensor.
  10.  
  11. Measure for 4.8-5.2 volts from the 5-volt reference circuit of the MAP sensor to a good ground, with a DMM.
    1. If more than 5.2 volts, then test the circuit for a short to voltage or faulty control module.
    2.  
    3. If less than 4.8 volts, then test the circuit for high resistance, an open, a short to ground, or an intermittent and poor connection or at the control module, or a faulty control module.
    4.  

  12.  
  13. Use a scan tool and observe the MAP sensor for less than 12 kPa.

    If the MAP sensor is more than 12 kPa then test the MAP sensor signal circuit for a short to voltage or a faulty control module.
     

  14.  
  15. Use a 3-amp fused jumper wire and connect it between the MAP sensor 5-volt reference circuit and the MAP sensor signal circuit.
  16.  
  17. Use a scan tool and observe the MAP sensor for more than 103 kPa.

    f the MAP sensor is less than 103 kPa, then test the MAP sensor signal circuit for a short to ground, an open, high resistance, or a faulty control module.
     

  18.  
  19. Turn OFF the ignition and allow the control module to power down.
  20.  
  21. Remove the MAP sensor from the engine vacuum source. Leave the MAP sensor connected to the engine harness.
  22.  
  23. Connect a J 23738-A Mityvac to the MAP sensor.
  24.  
  25. Turn ON the ignition, with the engine OFF.
  26.  
  27. Observe the MAP sensor pressure with the scan tool.
  28.  
  29. Apply vacuum to the MAP sensor with the J 23738-A in 1 inch Hg increments until 15 inches Hg is reached. Each 1 inch Hg should decrease MAP sensor pressure by 3-4 kPa. Monitor the MAP sensor pressure to see if the decrease in pressure is consistent.

    If the decrease in pressure is not consistent then, test for intermittent and poor connections at the MAP sensor. If connections test OK, replace the MAP sensor
     

  30.  
  31. Apply vacuum with the J 23738-A until 20 inches Hg is reached. Observe the MAP sensor pressure for less than 34 kPa. \

    If it is more than 34 kPa, test for an intermittent and for a poor connection at the MAP sensor. If connections test OK, replace the MAP sensor.
     

  32.  
  33. With a DMM measure for less than 5 ohms of resistance between the low reference circuit of the MAP sensor and battery negative post.

    If the resistance is more than 5 ohms, then test the low reference circuit for a high resistance or a faulty control module.
     

  34.  

 
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