Cavalier, Sunfire 2001-2005

Crankshaft Position Sensor

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Crankshaft Position System Variation Learn Procedure



2.2L Engines
  1. Install a scan tool.
  2.  
  3. With a scan tool, monitor the powertrain control module (PCM) for DTCs. If other DTCs are set, except DTC P1336, refer to Diagnostic Trouble Code (DTC) List for the applicable DTC that set.
  4.  
  5. With a scan tool, select the Crankshaft Position Variation Learn procedure.
  6.  
  7. Observe the fuel cut-off for the engine that you are performing the learn procedure on.
  8.  
  9. The scan tool instructs you to perform the following:

    Block the drive wheels.
     
    Apply the vehicles parking brake.
     
    Cycle the ignition from OFF to ON.
     
    Apply and hold the brake pedal.
     
    Start and idle the engine.
     
    Turn OFF the A/C.
     
    Place the vehicle's transmission in Park (A/T) or Neutral (M/T).
     
    The scan tool monitors certain component signals to determine if all the conditions are met to continue with the procedure. The scan tool only displays the condition that inhibits the procedure. The scan tool monitors the following components:
     



    Crankshaft position (CKP) sensors activity--If there is a CKP sensor condition, refer to the applicable DTC that set.
     
    Camshaft position (CMP) sensor activity--If there is a CMP sensor condition, refer to the applicable DTC that set.
     
    Engine coolant temperature (ECT)--If the engine coolant temperature is not warm enough, idle the engine until the engine coolant temperature reaches the correct temperature.
     

  10.  
  11. With the scan tool, enable the crankshaft position system variation learn procedure.
    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.

  12.  
  13. Slowly increase the engine speed to the RPM that you observed.
  14.  
  15. Immediately release the throttle when fuel cut-off is reached.
  16.  
  17. The scan tool displays Learn Status: Learned this ignition. If the scan tool does NOT display this message and no additional DTCs set, refer to Symptom Diagnosis No Codes section. If a DTC set, refer to the Diagnostic Trouble Code (DTC) List for the applicable DTC that set.
  18.  
  19. Turn OFF the ignition for 30 seconds after the learn procedure is completed successfully.
  20.  

2.4L Engines

A crankshaft position (CKP) system variation learn procedure must be performed any time a change is made to the crankshaft sensor to crankshaft relationship. Changing the crank sensor to crankshaft relationship will not allow the powertrain control module (PCM) to detect misfire at all speeds and loads accurately, resulting in a possible false misfire diagnostic trouble code (DTC) being set.

Removing a part for inspection and then reinstalling the same part is considered a disturbance. A false DTC P0300 could be set if this procedure is not performed.

The learn procedure is required after the following service procedures have been performed, regardless of whether or not DTC P1336 is set:



A PCM replacement
 
An engine replacement
 
A crankshaft replacement
 
A CKP sensor replacement
 
Any engine repair which disturbs the crankshaft/harmonic balancer relationship to the crankshaft position sensor
 

A fully warmed up engine is critical to learning the variation correctly. If a valid learn occurs, no other learns can be completed on that ignition cycle.

If the engine cuts out before the specified learn procedure engine speed or at normal fuel cut-off RPM, the PCM is not in the learn procedure mode. Review the crankshaft position system variation learn procedure and re-enable the learn procedure. Verify that the scan tool displays Test in Progress.


WARNING
Before performing the Crankshaft Position System Variation Learning Procedure always set the vehicle parking brake and block the drive wheels in order to prevent personal injury. Release the throttle immediately when the engine starts to decelerate in order to eliminate over revving the engine. Once the learn procedure is completed, the control module will return engine control to the operator and the engine will respond to the throttle position.


CAUTION
The battery must be fully charged and in good condition. Verify that the scan tool connection at the data link connector (DLC) is clean and tight before starting the crankshaft position (CKP) system variation learn procedure.

  1. Close the hood.
  2.  
  3. Block the drive wheels and set the vehicle parking brake.
  4.  
  5. Put the vehicle in Park or Neutral.
  6.  
  7. Turn all the accessories OFF.
  8.  
  9. Connect a scan tool.
  10.  
  11. Start and run the engine until the engine is at normal operating temperature 85C (185F).
  12.  
  13. With the engine still running, use the scan tool in order to enable the crankshaft position (CKP) system variation learn procedure.
  14.  
  15. Press and hold the brake pedal firmly and raise the engine speed to the specified value of 3,920 RPM, RELEASING the throttle as soon as the engine cuts out.
  16.  
  17. Verify with the scan tool that the crankshaft variation has been learned.
  18.  
  19. A fully warmed up engine is critical to learning the variation correctly. If a valid learn occurs, no other learns can be completed on that ignition cycle.
  20.  
  21. If the engine cuts out before the specified learn procedure engine speed or at normal fuel cut-off RPM, the PCM is not in the learn procedure mode. Review the crankshaft position system variation learn procedure and re-enable the learn procedure. Verify that the scan tool displays Test in Progress.
  22.  
  23. If the variation will not learn, perform this procedure up to 10 times.
  24.  

Scan Tool DisplayPossible Causes
Factors out of rangereluctor wheel-machining quality, a run out, or an incorrect air gap.
Opposing factors out of rangeDisturbance-Noise on the ckp sensor circuit. Reattempt the Learn Procedure.
Sum out of rangeengine is too cold. Reattempt the Learn Procedure.
Crank pulse count error.Crank or Cam sensor DTCs is set. Repair the affected DTC first

Excessive Crankshaft Variation Symptoms on 2.4L Engines

Operation



2.2L & 2.4L Engines

The crankshaft position (CKP) sensor is a permanent magnet generator, known as a variable reluctance sensor. The CKP sensor produces an AC voltage of different amplitude and frequency. The frequency depends on the velocity of the crankshaft. The AC voltage output depends on the crankshaft position and the battery voltage. The CKP sensor works in conjunction with a 7X reluctor wheel attached to the crankshaft. The CKP sensor produces 7 pulses for each revolution of the crankshaft. The pulse from the 10-degree notch 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 used for ignition timing, the fuel injector timing, misfire diagnostics and tachometer display. The CKP sensor is connected to the ECM by a signal circuit and a low reference circuit.

Removal & Installation



2.2L (L61) Engines
  1. Disconnect the battery.
  2.  
  3. Raise the vehicle.
  4.  
  5. Remove the front air deflector, if applicable.
  6.  
  7. Remove the starter.
  8.  
  9. Disconnect the Crankshaft Position (CKP) sensor electrical connector.
  10.  
  11. Remove the CKP sensor bolt.
  12.  
  13. Remove the CKP sensor.
  14.  

To install:

  1. Inspect the CKP sensor O-ring and lubricate with a mineral-based grease.
  2.  
  3. Gently insert the CKP sensor into the block.
  4.  
  5. Install the CKP sensor bolt. Tighten the CKP sensor bolt to 71 inch lbs. (8 Nm).
  6.  
  7. Reconnect the CKP sensor electrical connector.
  8.  
  9. Reinstall the starter.
  10.  
  11. Reinstall the front air deflector, if removed in previous step.
  12.  
  13. Lower the vehicle.
  14.  
  15. Reconnect the battery.
  16.  
  17. Perform the Crankshaft Variation Learn Procedure.
  18.  

2.2L (LN2) Engines
  1. Raise the vehicle
  2.  
  3. Remove the crankshaft position (CKP) sensor harness connector.
  4.  
  5. Remove the CKP sensor mounting bolt (2).
  6.  
  7. Remove the CKP sensor from the engine (1).
  8.  
  9. Inspect the CKP sensor O-ring for wear, cracks or leakage. Replace the O-ring if necessary
  10.  
  11. Installation is the reverse of the removal procedure. Tighten the sensor mounting bolt to 71 inch lbs. (8 Nm).
  12.  

2.4L Engines
  1. Raise and support the vehicle.
  2.  
  3. Disconnect the crankshaft position (CKP) sensor harness connector.
  4.  
  5. Remove the CKP sensor retaining bolt.
  6.  
  7. Remove the CKP sensor from the engine block.
  8.  
  9. Installation is the reverse of the removal procedure. Lubricate the O-ring. Tighten the sensor mounting bolt to 89 inch lbs. (10 Nm).
  10.  

 
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