LaCrosse 2006-2007

Barometric Pressure Sensor

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Operation



As a vehicle travels in different elevations, the barometric pressure changes. Based on the elevation above or below sea level, the pressure changes are compensated for through the vehicle electronics. As elevation increases, there is less overlying atmospheric mass, so that pressure decreases with increasing elevation.

The BARO sensor is a variable capacitance sensor used to determine altitude. The BARO signal affects injection timing and fuel quantity to optimize engine operation throughout all altitude conditions.

Removal & Installation



3.6L Engine
  1. Turn the ignition OFF.
  2.  
  3. Remove the Barometric Pressure (BARO) sensor electrical connector.
  4.  
  5. Remove the BARO sensor bolt.
  6.  
  7. Remove the BARO sensor.

    Click image to see an enlarged view

    Fig. Barometric Pressure (BARO) sensor location-3.6L engine

  8.  

To install:

  1. Install the BARO sensor.
  2.  
  3. Install the BARO sensor bolt. Tighten the BARO sensor bolt to 89 inch lbs. (10 Nm).
  4.  
  5. Install the BARO sensor electrical connector.

    Click image to see an enlarged view

    Fig. Barometric Pressure (BARO) sensor bolt installation-3.6L engine

  6.  

3.8L Engine
  1. Remove the fuel injector sight shield.
  2.  
  3. Disconnect the Barometric Pressure (BARO) sensor electrical connector.
  4.  
  5. Remove the BARO sensor retainer.
  6.  
  7. Remove the BARO sensor.

    Click image to see an enlarged view

    Fig. Barometric Pressure (BARO) sensor location-3.8L engine

  8.  

To install:

  1. Install the BARO sensor.
  2.  
  3. Install the BARO sensor retainer.
  4.  
  5. Connect the BARO sensor electrical connector.
  6.  
  7. Install the fuel injector sight shield.
  8.  

Testing



  1. Before beginning vehicle diagnosis, the following preliminary inspections/tests must be performed:

    Ensure that the battery is fully charged
     
    Ensure that the battery cables are clean and tight
     
    Inspect for any open fuses
     
    Ensure that the grounds are clean, tight, and in the correct location
     
    Inspect the easily accessible systems or the visible system components for obvious damage or conditions that could cause the concern. This would include checking to ensure that all connections/connectors are fully seated and secured
     
    Inspect for aftermarket devices that could affect the operation of the system
     
    Search for applicable service bulletins
     

  2.  
  3. Install a scan tool. Verify that the scan tool powers up.
  4.  
  5. With the ignition ON, engine OFF, verify communication with all of the control modules on the vehicle.
  6.  
  7. Turn ON the ignition, with the engine OFF.
  8.  
  9. Observe the Barometric Pressure (BARO) sensor parameter on a scan tool while moving the related harness connectors at the BARO sensor and at the Engine Control Module (ECM).

    The BARO parameter should remain steady and not change by more than 3 kPa
     
    If the BARO parameter changes more than 3 kPa, check the integrity of the connectors and the immediate wiring
     

  10.  
  11. Turn OFF the ignition.
  12.  
  13. Disconnect the BARO sensor.
  14.  
  15. Turn ON the ignition, with the engine OFF.
  16.  
  17. Observe the BARO volts parameter with a scan tool.

    The voltage should be within the range of 4.9-5.2 volts
     

  18.  
  19. Connect a fused jumper wire between the signal circuit of the BARO sensor and the ECM housing.
  20.  
  21. Observe the BARO volts parameter with a scan tool.

    The voltage should read 0.00 volts
     

  22.  
  23. Set up a Digital Multi-Meter (DMM) to test amperage on the 400 mA scale.
  24.  
  25. Measure the amperage between the 5-volt reference circuit of the BARO sensor and the ECM housing.

    The amperage should be no more than 80 mA
     

  26.  
  27. Turn OFF the ignition.
  28.  
  29. Remove the ECM fuse, or the PCM/ETC fuse, from the underhood electrical center.
    WARNING
    Do NOT use a test lamp to test the continuity of the circuit. Damage to the control module may occur due to excessive current draw.

  30.  
  31. Measure the resistance between the low reference circuit of the BARO sensor and the ECM housing with a DMM.

    The resistance should not be more than 5 ohms
     

  32.  
  33. Test for shorted terminals and for poor connections at the BARO sensor.
  34.  
  35. If all circuits are functioning properly replace the BARO sensor.
  36.  

 
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