Cobalt 2006-2008, G5 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 greatest 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 least manifold pressure occurs when the vehicle is idling or decelerating. MAP can range from 10 kPa, when pressures are less, to as great as 104 kPa, depending on the current BARO. The ECM monitors the MAP sensor signal for pressure outside of the normal range.

Removal & Installation



2.0L Engine
Supercharger Inlet Pressure (Scip) Sensor


Click image to see an enlarged view

Fig. Manifold Absolute Pressure (MAP) SCIP sensor location-2.0L engine

  1. Disconnect the Supercharger Inlet Pressure (SCIP) sensor harness connector.
  2.  
  3. Remove the SCIP sensor (1) from the supercharger.
    WARNING
    If the SCIP sensor seal is damaged, the SCIP sensor must be replaced.

  4.  
  5. Inspect the seal for damage.
  6.  

To install:


NOTE
Use the new SCIP sensor seal provided with the new SCIP sensor.

  1. Install the SCIP sensor (1) into the intake manifold. Tighten the bolt to 89 inch lbs. (10 Nm).
  2.  
  3. Connect the SCIP sensor harness connector.
  4.  

Temperature Manifold Absolute Pressure (Tmap) Sensor


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Fig. Manifold Absolute Pressure (MAP) TMAP sensor location-2.0L engine

  1. Disconnect the Temperature Manifold Absolute Pressure (TMAP) sensor harness connector.
  2.  
  3. Remove the TMAP sensor from the intake manifold.
    WARNING
    If the TMAP sensor seal is damaged, the TMAP sensor must be replaced.

  4.  
  5. Inspect the seal for damage.
  6.  

To install:


NOTE
Use the new TMAP sensor seal provided with the new TMAP sensor.

  1. Install the TMAP sensor into the intake manifold. Tighten the bolt to 89 inch lbs. (10 Nm).
  2.  
  3. Connect the TMAP sensor harness connector.
  4.  

2.2L & 2.4L Engines


Click image to see an enlarged view

Fig. Manifold Absolute Pressure (MAP) sensor location-2.2L & 2.4L engines

  1. Remove the throttle body.
  2.  
  3. Disconnect the engine harness electrical connector from the Manifold Absolute Pressure (MAP) sensor.
  4.  
  5. Remove the MAP sensor and seal.
  6.  

To install:

  1. Lubricate the NEW MAP sensor seal with clean engine oil.
  2.  
  3. Install the MAP sensor into the intake manifold.
  4.  
  5. Connect the engine harness electrical connector to the MAP sensor.
  6.  
  7. Install the throttle body.
  8.  

Testing



  1. Verify the integrity of the entire air induction system by inspecting for the following conditions:

    Any damage to, or hairline fractures of, the MAP sensor housing
     
    Loose or improper installation
     
    Any vacuum leak
     

  2.  
  3. Verify that restrictions do not exist in the MAP sensor port or vacuum source.
  4.  
  5. Determine the current vehicle testing altitude. Ignition ON, observe the scan tool BARO Sensor parameter.
  6.  
  7. Use the scan tool and compare the MAP Sensor parameter to a known good vehicle, under various operating conditions.
  8.  

Circuit Testing


Click image to see an enlarged view

Fig. Manifold Absolute Pressure (MAP) connector end view-2.0L & 2.2L engines



Click image to see an enlarged view

Fig. Manifold Absolute Pressure (MAP) connector end view-2.4L engine


NOTE
All electrical components and accessories must be turned OFF, and allowed to power down.

  1. With the ignition OFF, disconnect the MAP harness connector at the MAP sensor.
  2.  
  3. Test for less than 5 ohms of resistance between the low reference circuit terminal 2 and ground-2.0L & 2.2L (A and ground-2.4L).
    1. If greater than the specified range, test the low reference circuit for an open/high resistance.
    2.  
    3. If the circuit tests normal, replace the ECM.
    4.  

  4.  
  5. With the ignition ON, test for 4.8-5.2 volts between the 5 volt reference circuit terminal 1 and ground-2.0L & 2.2L (C and ground-2.4L).
    1. If less than the specified range, test the 5 volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
    2.  
    3. If greater than the specified range, test the 5 volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
    4.  

  6.  
  7. Verify the scan tool MAP sensor parameter is less than 1 kPa.
    1. If greater than the specified range, test the signal circuit terminal 3-2.0L & 2.2L for a short to voltage.
    2.  
    3. If the circuit tests normal, replace the ECM.
    4.  

  8.  
  9. Install a 3A fused jumper wire between the signal circuit terminal 3-2.0L & 2.2L and the 5 volt reference circuit terminal 1-2.0L & 2.2L. Verify the scan tool MAP sensor parameter is greater than 126 kPa.
    1. If less than the specified range, test the signal circuit terminal 3-2.0L & 2.2L for a short to ground or an open/high resistance.
    2.  
    3. If the circuit tests normal, replace the ECM.
    4.  

  10.  
  11. If all circuits test normal, test or replace the MAP sensor.
  12.  

Component Testing

NOTE
You must perform the circuit/system testing, in order to verify the integrity of the MAP sensor circuits, before proceeding with the component testing.

  1. Turn ON the ignition, with the engine OFF, and remove the MAP sensor.
  2.  
  3. Install a 3A fused jumper wire between the 5 volt reference circuit terminal 1-2.0L & 2.2L and the corresponding terminal of the MAP sensor.
  4.  
  5. Install a jumper wire between the low reference circuit terminal 2-2.0L & 2.2L of the MAP sensor and ground.
  6.  
  7. Install a jumper wire at terminal 3-2.0L & 2.2L of the MAP sensor.
  8.  
  9. Connect a DMM between the jumper wire from terminal 3 of the MAP sensor and ground.
  10.  
  11. Install the J 35555 to the MAP sensor vacuum port. Slowly apply vacuum to the sensor while observing the voltage on the DMM. The voltage should vary between 0-5.2 volts, without any spikes or dropouts.
  12.  
  13. If the voltage is not within the specified range or is erratic, replace the MAP sensor.
  14.  

 
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