Envoy, Rainer, Trailblazer 2006-2007

Crankshaft Position Sensor

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Operation



4.2L Engine

The crankshaft position (CKP) sensor is a permanent magnet generator, known as a variable reluctance sensor. The magnetic field of the sensor is altered by a crankshaft mounted reluctor wheel that has seven machined slots, 6 of which are equally spaced 60 degrees apart. The seventh slot is spaced 10 degrees after one of the 60 degree slots. The CKP sensor produces seven pulses for each revolution of the crankshaft. The pulse from the 10 degree slot is known as the sync pulse. The sync pulse is used to synchronize the coil firing sequence with the crankshaft position. The CKP sensor is connected to the powertrain control module (PCM) by a signal circuit and a low reference circuit.

5.3L Engine

The crankshaft position (CKP) sensor is a three wire sensor based on the magneto resistive principle. A magneto resistive sensor uses two magnetic pickups between a permanent magnet. As an element such as a reluctor wheel passes the magnets the resulting change in the magnetic field is used by the sensor electronics to produce a digital output pulse. The engine control module (ECM) supplies a 12-volt, low reference, and signal circuit to the CKP sensor. The sensor returns a digital ON/OFF pulse 24 times per crankshaft revolution.

6.0L Engine

The Crankshaft Position (CKP) sensor is a 3-wire sensor that provides a digital output signal. The wire circuits consist of an Engine Control Module (ECM) supplied 5-volt reference circuit, a low reference circuit between the CKP sensor and the ECM, and an output signal circuit from the CKP sensor to the ECM. The CKP sensor detects magnetic flux changes of the teeth and slots of the 58-tooth reluctor on the crankshaft. The CKP sensor provides an ON/OFF DC voltage of varying frequency, with 58 output pulses per each crankshaft revolution. The frequency of the CKP sensor output signal depends on the speed of the crankshaft. The CKP sensor sends a digital square wave signal, which represents an image of the teeth on the reluctor wheel, to the ECM. The 12 degree reference gap on the reluctor wheel is used to identify crankshaft position. The CKP information, along with the Camshaft Position (CMP) sensor information is used to determine the correct time and sequence for fuel injection, ignition spark events, detect cylinder misfire, and the camshaft to crankshaft relative position.

Removal & Installation



4.2L Engine
  1. Disconnect the negative battery cable.
  2.  
  3. Raise and safely support the front of the vehicle securely on jackstands.
  4.  
  5. Disconnect the CKP sensor harness connector.
  6.  
  7. Remove the CKP sensor retaining bolt.
  8.  
  9. Remove the CKP sensor from the engine block.

    Click image to see an enlarged view

    Fig. Location of the Crankshaft Position (CKP) sensor-4.2L engine

  10.  

To install:

  1. Inspect the sensor O-ring for wear cracks or leakage and replace if necessary. Lubricate the new O-ring with engine oil before installation.
  2.  
  3. Install the CKP sensor into the engine block and tighten the bolt to 89 inch lbs. (10 Nm).
  4.  
  5. Install the CKP sensor retaining bolt.
  6.  
  7. Connect the CKP sensor harness connector.
  8.  
  9. Lower the vehicle.
  10.  
  11. Perform the crankshaft position system variation learn procedure as follows:
    1. Install a scan tool.
    2.  
    3. Monitor the ECM for DTCs with a scan tool. If other DTCs are set, except DTC P0315, refer to Diagnostic Trouble Code (DTC) List - Vehicle for the applicable DTC that set.
    4.  
    5. With a scan tool, select the CKP system variation learn procedure and perform the following:

      Observe the fuel cut-off for the applicable engine
       
      Block the drive wheels
       
      Set the parking brake
       
      Place the vehicle's transmission in Park or Neutral
       
      Turn the A/C OFF
       
      Cycle the ignition from OFF to ON
       
      Apply and hold the brake pedal for the duration of the procedure
       
      Start and idle the engine
       
      Accelerate to wide open throttle (WOT). The engine should not accelerate beyond the calibrated fuel cut-off RPM value noted earlier. Release the throttle immediately if the value is exceeded.
       
      While the learn procedure is in progress, release the throttle immediately when the engine starts to decelerate. The engine control is returned to the operator and the engine responds to throttle position after the learn procedure is complete.
       
      Release the throttle when fuel cut-off occurs
       

    6.  
    7. The scan tool displays Learn Status: Learned this Ignition. If the scan tool indicates that DTC P0315 ran and passed, the CKP variation learn procedure is complete. If the scan tool indicates DTC P0315 failed or did not run, refer to DTC P0315. If any other DTCs set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for the applicable DTC that set.
    8.  
    9. Turn OFF the ignition for 30 seconds after the learn procedure is completed successfully.
    10.  

  12.  
  13. Connect the negative battery cable.
  14.  

5.3L And 6.0L Engines
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the starter.
  4.  
  5. Disconnect the electrical connector (2) from the CKP sensor (1).
  6.  
  7. Clean the area around the CKP sensor before removal in order to avoid debris from entering the engine.
  8.  
  9. Remove the CKP sensor bolt.
  10.  
  11. Remove the CKP sensor.

    Click image to see an enlarged view

    Fig. Location CKP sensor-5.3L and 6.0L engines

  12.  

To install:

  1. Install the CKP sensor.
  2.  
  3. Install the CKP sensor bolt and tighten to 18 ft. lbs. (25 Nm).
  4.  
  5. Connect the electrical connector (2) to the CKP sensor (1).
  6.  
  7. Install the starter.
  8.  
  9. Perform the crankshaft position system variation learn procedure as follows:
    1. Install a scan tool.
    2.  
    3. Monitor the ECM for DTCs with a scan tool. If other DTCs are set, except DTC P0315, refer to Diagnostic Trouble Code (DTC) List - Vehicle for the applicable DTC that set.
    4.  
    5. With a scan tool, select the CKP system variation learn procedure and perform the following:

      Accelerate to wide open throttle (WOT)
       
      Release throttle when fuel cut-off occurs
       
      Observe fuel cut-off for applicable engine
       
      Engine should not accelerate beyond calibrated RPM value
       
      Release throttle immediately if value is exceeded
       
      Block drive wheels
       
      Set parking brake
       
      DO NOT apply brake pedal
       
      Cycle ignition from OFF to ON
       
      Apply and hold brake pedal
       
      Start and idle engine
       
      Turn A/C OFF
       
      Vehicle must remain in Park or Neutral
       

    6.  
    7. The scan tool displays Learn Status: Learned this Ignition. If the scan tool indicates that DTC P0315 ran and passed, the CKP variation learn procedure is complete. If the scan tool indicates DTC P0315 failed or did not run, refer to DTC P0315. If any other DTCs set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for the applicable DTC that set.
    8.  
    9. Turn OFF the ignition for 30 seconds after the learn procedure is completed successfully.
    10.  

  10.  
  11. Connect the negative battery cable.
  12.  

Testing



4.2L Engine

DTC P0336

Click image to see an enlarged view

Fig. Crankshaft Position (CKP) sensor connector end view-4.2L engine

  1. Start the engine.
  2.  
  3. Observe the Crankshaft Position (CKP) active counter on the scan tool. If there is no CKP active counter increment, then test the CKP sensor signal circuit of the sensor for an intermittent condition. If there is a CKP active counter increment, then proceed to the next step.
  4.  
  5. Observe the Freeze Frame/Failure Records for this Diagnostic Trouble Code (DTC).
  6.  
  7. Turn OFF the ignition for 30 seconds.
  8.  
  9. Start the engine.
  10.  
  11. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
  12.  
  13. If the DTC failed this ignition, then proceed to the next step. If the DTC did not fail this ignition, then test for an intermittent condition.
  14.  
  15. Test the CKP sensor signal circuit of the CKP sensor for an intermittent condition.
  16.  
  17. Test the low reference circuit of the CKP sensor for an intermittent condition.
  18.  
  19. Test for an intermittent and for a poor connection at the Powertrain Control Module (PCM).
  20.  
  21. Test for an intermittent and for a poor connection at the CKP sensor.
  22.  
  23. Remove the CKP sensor. Visually inspect the CKP sensor for the following conditions:

    Physical damage
     
    Loose or improper installation
     
    Wiring routed too closely to secondary ignition components
     

  24.  
  25. The following conditions may cause this DTC to set:

    Electromagnetic interference in the CKP sensor circuits
     
    Foreign material passing between the CKP sensor and the reluctor wheel
     
    Insufficient fuel
     

  26.  
  27. If no such conditions exist, continue.
  28.  
  29. Visually inspect the CKP reluctor wheel for the following conditions:

    Physical damage
     
    Improper installation
     
    Excessive play or looseness
     

  30.  
  31. If no such conditions exist, replace the CKP sensor. If any of these conditions do exist, repair them and then continue.
  32.  
  33. Clear the DTCs with a scan tool.
  34.  
  35. Turn OFF the ignition for 30 seconds.
  36.  
  37. Start the engine.
  38.  
  39. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
  40.  
  41. If the DTC failed this ignition, perform this procedure again starting from the first step. If the DTC did not fail this ignition, continue.
  42.  
  43. Observe the Capture Info with a scan tool.
  44.  
  45. Check for any undiagnosed DTCs.
  46.  

5.3L And 6.0L Engines

DTC P0335

Click image to see an enlarged view

Fig. Crankshaft Position (CKP) sensor connector end view-5.3L and 6.0L engines

  1. Attempt to start the engine. If the engine starts and continues to run, proceed to the next step. If the engine does not start, jump to step 7.
  2.  
  3. Observe the Freeze Frame/Failure Records for this Diagnostic Trouble Code (DTC).
  4.  
  5. Turn OFF the ignition for 30 seconds.
  6.  
  7. Start the engine.
  8.  
  9. Operate the vehicle within the conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. If the DTC failed this ignition, continue. If it did not fail this ignition, test for intermittent/poor connections.
  10.  
  11. Raise the vehicle.
  12.  
  13. Disconnect the Crankshaft Position (CKP) sensor connector.
  14.  
  15. Turn ON the ignition, with the engine OFF.
  16.  
  17. Measure the voltage from the 12-volt reference circuit of the CKP sensor to a good ground with a Digital Multi-Meter (DMM).
  18.  
  19. If the voltage measures above 11.8V, continue, If It measures below 11.8V, test the 12-volt reference circuit for the following conditions:

    An open
     
    A short to ground
     
    High resistance
     

  20.  
  21. If any of these conditions are found, continue and if not, test the 12V reference circuit for an open, short-to-ground or high resistance.
  22.  
  23. Measure the voltage between the 12-volt reference circuit of the CKP sensor and the low reference circuit of the CKP sensor with a Digital Multi-Meter (DMM). If the voltage measure above 11.8V continue, and If It measures below 11.8V, test the low reference circuit for an open, a short-to-voltage or high Resistance
  24.  
  25. Momentarily connect a test lamp between the CKP sensor signal circuit and the 12-volt reference of the CKP sensor. If the fuel pump operates when the test lamp is applied to the CKP sensor signal circuit, skip to step 20, if it does not, then skip to step 18.
  26.  
  27. Test the 12-volt reference circuit for the following conditions:

    An open
     
    A short to ground
     
    High resistance
     

  28.  
  29. If the condition was found and corrected, skip to step 27, if no such conditions exist, then skip to step 26.
  30.  
  31. Test the low reference circuit for the following conditions:

    An open
     
    A short to voltage
     
    High Resistance
     

  32.  
  33. If the condition was found and corrected, skip to step 27, if no such conditions exist, then skip to step 26.
  34.  
  35. Test the CKP sensor signal circuit for the following conditions:

    An open
     
    A short to ground
     
    A short to voltage
     
    High resistance
     

  36.  
  37. If the condition was found and corrected, skip to step 27, if no such conditions exist, then skip to step 26.
  38.  
  39. Remove the CKP sensor.
  40.  
  41. Visually inspect the CKP sensor for the following conditions:

    Physical damage
     
    Loose or improper installation
     
    Wiring routed too closely to the secondary ignition components
     

  42.  
  43. The following conditions may cause this DTC to set:

    Excessive air gap between the CKP sensor and the reluctor wheel
     
    The CKP sensor coming in contact with the reluctor wheel
     
    Foreign material passing between the CKP sensor and the reluctor wheel
     

  44.  
  45. If the condition was found and corrected, skip to step 27, if no such conditions exist, then continue.
  46.  
  47. Visually inspect the CKP sensor reluctor wheel for the following conditions:

    Loose or improper installation
     
    Physical damage
     
    Excessive end play or looseness
     

  48.  
  49. If no such conditions are found, replace the CKP sensor.
  50.  
  51. Test for poor connections at the CKP sensor and if the connections are okay, test for poor connections at the Engine Control Module (ECM) and if it is not a poor connection, replace the ECM.
  52.  
  53. Clear the DTCs with a scan tool.
  54.  
  55. Turn OFF the ignition for 30 seconds.
  56.  
  57. Start the engine.
  58.  
  59. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
  60.  
  61. If the DTC failed this ignition, perform this procedure again starting from the first step. If the DTC did not fail this ignition, continue.
  62.  
  63. Observe the Capture Info with a scan tool.
  64.  
  65. Check for any undiagnosed DTCs.
  66.  

 
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