LaCrosse 2006-2007

Crankshaft Position Sensor

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Operation



The Crankshaft Position (CKP) sensor is a permanent magnet generator known as a variable reluctance sensor. The CKP sensor produces an AC voltage of varying amplitude and frequency. The frequency depends on the velocity of the crankshaft. The AC output depends on the crankshaft position and the battery voltage. The CKP sensor works in conjunction with a reluctor wheel attached to the crankshaft. As each reluctor wheel tooth rotates past the CKP sensor, the resulting change in the magnetic field creates an ON/OFF pulse. The PCM processes the pulses to create a pattern that enables the PCM to determine the crankshaft position. The PCM can synchronize the ignition timing, the fuel injector timing, and the spark knock control based on the CKP sensor and the Camshaft Position (CMP) sensor inputs. The CKP sensor is also used to detect misfire and for tachometer display. The PCM learns the variations between different speed and load conditions to correctly detect misfires. The CKP sensor circuits consist of a signal circuit and a low reference circuit. The two wires are twisted together to prevent electromagnetic interference on the CKP sensor circuits.

Removal & Installation



3.6L Engine
  1. Turn the ignition OFF.
  2.  
  3. Raise and support the vehicle.
  4.  
  5. Reposition the wiring harness heat shield to obtain access.
  6.  
  7. Disconnect the Crankshaft Position (CKP) electrical connector (3).
  8.  
  9. Remove the crankshaft sensor bolt.
  10.  
  11. Remove the crankshaft sensor.

    Click image to see an enlarged view

    Fig. CKP sensor location-3.6L engine

  12.  

To install:

  1. Install the crankshaft position sensor.
  2.  
  3. Install the crankshaft position sensor bolt. Tighten the crankshaft position sensor bolt to 89 inch lbs. (10 Nm).
  4.  
  5. Connect the CKP electrical connector (3).
  6.  
  7. Install the wiring harness heat shield to the oil level indicator tube.
  8.  
  9. Lower the vehicle.
  10.  

3.8L Engine
  1. Disconnect the negative battery cable.
  2.  
  3. Raise and support the vehicle.
  4.  
  5. Remove the crankshaft damper (harmonic balancer). Refer to Crankshaft Damper, removal and installation.
  6.  
  7. Disconnect the Crankshaft Position (CKP) sensor electrical connector.
    WARNING
    Do not use a pry bar when removing the CKP sensor shield.

  8.  
  9. Remove the CKP sensor shield (1).

    Click image to see an enlarged view

    Fig. Remove the CKP sensor shield-3.8L engine

  10.  
  11. Remove the CKP sensor studs.
  12.  
  13. Remove the CKP sensor.

    Click image to see an enlarged view

    Fig. CKP sensor location-3.8L engine

  14.  

To install:

  1. Install the CKP sensor.
  2.  
  3. Install the CKP sensor studs. Tighten the studs to 22 ft. lbs. (30 Nm).
  4.  
  5. Install the CKP sensor shield (1).
  6.  
  7. Connect the CKP sensor electrical connector.
  8.  
  9. Install the crankshaft damper. Refer to Crankshaft Damper, removal and installation.
  10.  
  11. Lower the vehicle.
  12.  
  13. Connect the negative battery cable.
  14.  
  15. Perform the CKP system Variation Learn Procedure. Refer to Crankshaft Position (CKP) Sensor, Testing, Variation Learn Procedure for CKP.
  16.  

Testing





Click image to see an enlarged view

Fig. CKP sensor connector end view-3.6L engine



Click image to see an enlarged view

Fig. CKP sensor connector end view-3.8L engine

During normal operation the PCM controls all ignition functions. If either the Crankshaft Position (CKP) or Camshaft Position (CMP) sensor signal is lost, the engine will continue to run because the PCM will default to a limp home mode using the remaining sensor input. Diagnostic trouble codes are available to accurately diagnose the ignition system with an OBD2 scan tool.

  1. Inspect the CKP sensor for correct installation. Remove the CKP sensor from the engine and inspect the sensor O-ring for damage. If the sensor is loose, incorrectly installed, or damaged, replace the CKP sensor.
  2.  
  3. Engage the CKP sensor harness connector to the CKP sensor.
  4.  
  5. Connect the scan tool to the diagnostic connector.
  6.  
  7. With the ignition ON, engine OFF observe the CKP active counter parameter on the scan tool.
  8.  
  9. Pass a flat steel object across the tip of the sensor repeatedly. The CKP active counter parameter should increment with each pass of the steel object.
  10.  
  11. If the parameter does not increment, replace the CKP sensor.
  12.  

Variation Learn Procedure For CKP

The Crankshaft Position (CKP) system variation learn procedure is required when the following service procedures have been performed, regardless of whether DTC P0315 is set:



Engine replacement
 
Engine Control Module (ECM) replacement
 
Crankshaft damper replacement
 
Crankshaft replacement
 
CKP sensor replacement
 
Any engine repairs which disturb the crankshaft to CKP sensor relationship
 

The scan tool monitors certain component signals to determine if all the conditions are met to continue with the CKP system variation learn procedure. The scan tool only displays the condition that inhibits the procedure. The scan tool monitors the following components:



CKP sensor activity. If there is a CKP sensor condition, refer to the applicable DTC that was set.
 
Camshaft Position (CMP) signal activity. If there is a CMP signal condition, refer to the applicable DTC that was set.
 
Engine Coolant Temperature (ECT). If the ECT is not warm enough, idle the engine until the ECT reaches the correct temperature.
 

  1. Install a scan tool.
  2.  
  3. Monitor the ECM for DTC-s with a scan tool. If other DTC's are set, except DTC P0315, refer to the applicable DTC information for that code.
  4.  
  5. With a scan tool, select the CKP system variation learn procedure and perform the following:
    1. Observe the fuel cut-off for the applicable engine.
    2.  
    3. Block the drive wheels.
    4.  
    5. Set the parking brake.
    6.  
    7. Place the vehicle's transmission in Park or Neutral.
    8.  
    9. Turn the Air Conditioning (A/C) OFF .
    10.  
    11. Cycle the ignition from OFF to ON .
    12.  
    13. Apply and hold the brake pedal for the duration of the procedure.
    14.  
    15. Start and idle the engine.
    16.  
    17. Accelerate to Wide Open Throttle (WOT). The engine should not accelerate beyond the calibrated fuel cut-off RPM value noted above. Release the throttle immediately if the value is exceeded.
      NOTE
      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.

    18.  
    19. Release the throttle when fuel cut-off occurs.
    20.  

  6.  
  7. The scan tool displays Learn Status: Learned this Ignition.
    1. If the scan tool indicates that DTC P0315 ran and passed, the CKP variation learn procedure is complete.
    2.  
    3. If the scan tool indicates DTC P0315 failed or did not run, refer to DTC P0315 test procedures.
    4.  
    5. If any other DTC-s are set, refer to a Diagnostic Trouble Code (DTC) list for the applicable DTC that was set.
    6.  

  8.  
  9. Turn OFF the ignition for 30 seconds after the learn procedure is completed successfully in order to store the CKP system variation values in the PCM memory.
  10.  

 
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