S&T Series Blazer, Bravada, Envoy, Jimmy, Rainier, Trailblazer, Xtreme

Crankshaft Position (CKP) Sensor

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Crankshaft Variation Learn Procedure



The crankshaft position system variation compensating values are stored in the PCM non-volatile memory after a learn procedure has been performed. If the actual crankshaft position system variation is not within the crankshaft position system variation compensating values stored in the PCM, DTC P0300 may set. Refer to Diagnostic Aids for DTC P0300. The Crankshaft Position System Variation Learn Procedure should be performed if any of the following conditions are true:



DTC P1336 is set.
 
The PCM has been replaced.
 
The engine has been replaced.
 
The crankshaft has been replaced.
 
The crankshaft harmonic balancer has been replaced.
 
The crankshaft position sensor has been replaced.
 


CAUTION
The scan tool crankshaft position system variation learn function will be inhibited if engine coolant temperature is less than 70C (158F). Allow the engine to warm to at least 70C (158F) before attempting the crankshaft position system variation learn procedure. The scan tool crankshaft position system variation learn function will be inhibited if any Powertrain DTCs other than DTC P1336 are set before or during the crankshaft position system variation learn procedure. Diagnose and repair any DTCs if set. Refer to applicable DTCs. The crankshaft position system variation learn function will be inhibited if the PCM detects a malfunction involving the camshaft position signal circuit, the 3X reference circuit, or the 24X reference circuit. If a malfunction has been indicated, refer to the following list to diagnoses the system or sensor.



DTC P0336 Crankshaft Position (CKP) Sensor Circuit.
 
DTC P0341 Camshaft Position (CMP) Sensor Performance.
 
DTC P1374 Crankshaft Position (CKP) High to Low Resolution Frequency Correlation.
 

The scan tool crankshaft position system variation learn function will not be enabled until engine coolant temperature reaches 158F (70C). Selecting the crankshaft position system variation learn procedure on the scan tool will command the PCM to enable CKP system variation learn fuel cutoff and allow the crankshaft position system variation compensating values to be stored in the PCM. The PCM must detect an engine speed of 5150 RPM (CKP system variation learn fuel cutoff) during the crankshaft position system variation learn procedure to store the crankshaft position system variation compensating values and complete the procedure.


CAUTION
Set the vehicle parking brake and block the drive wheels when performing the Crankshaft Position System Variation Learning Procedure in order to prevent personal injury. Release the throttle when the engine reaches the second fuel cut off. Leaving the throttle open during the fuel cut off will allow the engine to decel at an even rate. Once the learn procedure is completed, the PCM will return the engine control to the operator and the engine will respond to the throttle position.

  1. Set the parking brake.
  2.  
  3. Block the drive wheels.
  4.  
  5. Ensure the hood is closed.
  6.  
  7. Start the engine and allow engine coolant temperature to reach at least 70C (158F).
  8.  
  9. Turn off the ignition switch.
  10.  
  11. Select and enable the crankshaft position variation learn procedure with the scan tool.
  12.  
  13. Start the vehicle.
  14.  
  15. Apply and hold the service brake pedal firmly.
  16.  
  17. Ensure the transaxle is in park.
  18.  
  19. Increase accelerator pedal position and hold until the fuel cutoff is reached at 5150 RPM. Release the accelerator pedal after the second fuel cutoff has been reached.
  20.  
  21. The crankshaft position system variation compensating values are learned when the RPM decreases back to idle. If the procedure terminates.
  22.  
  23. Observe DTC status for DTC P1336.
  24.  
  25. If the scan tool indicates that DTC P1336 ran and passed, the crankshaft position system variation learn procedure is complete. If the scan tool indicates DTC P1336 failed or not run, determine if other DTCs have set. If DTCs other than P1336 are not set, repeat the crankshaft position system variation learn procedure as necessary.
  26.  


NOTE
For additional diagnostic information, refer to DTC P1336.

  1. Install a scan tool.
  2.  
  3. With a scan tool, monitor the powertrain control module 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:
  10.  
  11. Block the drive wheels.
  12.  
  13. Apply the vehicles parking brake.
  14.  
  15. Cycle the ignition from OFF to ON.
  16.  
  17. Apply and hold the brake pedal.
  18.  
  19. Start and idle the engine (with A/C OFF).
  20.  
  21. Place the vehicle's transmission in Park (A/T) or Neutral (M/T).
  22.  
  23. 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.
     

  24.  
  25. 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.

  26.  
  27. Slowly increase the engine speed to the RPM that you observed.
  28.  
  29. Immediately release the throttle when fuel cut-off is reached.
  30.  
  31. 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 Diagnostic Trouble Code (DTC) List for the applicable DTC that set.
  32.  
  33. Turn OFF the ignition for 30 seconds after the learn procedure is completed successfully.
  34.  

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.  

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

Description & Operation



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. This system uses two sensors within the same housing for the V6 engine, and two separate sensors for the V8 engine. The PCM supplies each sensor a 12-volt reference, low reference, and a signal circuit. The signal circuit returns a digital ON/OFF pulse 24 times per crankshaft revolution.

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



  1. Raise and support the vehicle.
  2.  
  3. Remove the air deflector.
  4.  
  5. Remove the oil filter adaptor.
  6.  
  7. Disconnect the crankshaft position sensor electrical connector.
  8.  
  9. Remove the crankshaft sensor retaining bolt.
  10.  
  11. Remove the crankshaft sensor.

    Click image to see an enlarged view

    Fig. Removing CKP Sensors

  12.  

To install:


NOTE
Inspect the crankshaft sensor O-ring for wear or damage. If a problem is found, replace the O-ring.

  1. Lubricate the crankshaft sensor O-ring with clean engine oil.
    NOTE
     Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  2.  
  3. Install the crankshaft sensor and the retaining bolt. Tighten the retaining bolt between 10 Nm (89 inch lbs.).
  4.  
  5. Connect the crankshaft position sensor electrical connector.
  6.  
  7. Install the oil filter adaptor.
  8.  
  9. Install the air deflector.
  10.  
  11. Lower the vehicle.
  12.  
  13. Operate the engine and inspect crankshaft sensor for engine oil leaks.
  14.  
  15. Perform the CKP System Variation Learn Procedure.
  16.  

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.  

3.1L & 3.4L-24x Type
  1. Turn OFF the ignition.
  2.  
  3. Remove the serpentine drive belt from crankshaft pulley.
  4.  
  5. Raise the vehicle on hoist.
  6.  
  7. Remove the crankshaft harmonic balancer retaining bolt.
  8.  
  9. Remove the crankshaft harmonic balancer.
  10.  
  11. Note the routing of sensor harness before removal.
  12.  
  13. Remove the harness retaining clip with bolt.
  14.  
  15. Disconnect the sensor electrical connector.
  16.  
  17. Remove the sensor bolts.
  18.  
  19. Remove the sensor.
  20.  

To install:

  1. Install the 24X Crankshaft Position Sensor with bolts and route harness as noted during removal.
  2.  
  3. Install the harness retaining clip with bolt. Tighten the bolts to 8 ft. lbs. (10 Nm).
  4.  
  5. Connect the sensor electrical connector.
  6.  
  7. Install the balancer on the crankshaft.
  8.  
  9. Apply thread sealer to threads of the crankshaft harmonic balancer bolt. Tighten the bolt to 110 ft. lbs. (150 Nm).
  10.  
  11. Lower vehicle.
  12.  
  13. Reinstall the serpentine drive belt.
  14.  
  15. Perform the CKP System Variation Learn Procedure.
  16.  

3.1L & 3.4L-7x Type
  1. Remove the negative battery cable.
  2.  
  3. Turn the steering wheel fully to the left.
  4.  
  5. Raise vehicle on hoist.
  6.  
  7. Disconnect the electrical connector.
  8.  
  9. Remove the retaining bolt.
  10.  
  11. Remove the sensor from the engine.
  12.  
  13. If the sensor is not being replaced inspect for wear, cracks, or leakage. Replace the O-ring if necessary.
  14.  
  15. Lubricate the new O-ring with clean engine oil before installing. To install:
  16.  
  17. Install the sensor into the block.
  18.  
  19. Reinstall the retainer bolt to hold sensor to block face. Tighten the bolt to 71 inch lbs. (8 Nm).
  20.  
  21. Connect the electrical connector.
  22.  
  23. Lower the vehicle. Reconnect the negative battery cable.
  24.  

3.5L
  1. Disconnect the negative battery cable.
  2.  
  3. Raise and support the vehicle.
  4.  
  5. Remove the starter motor.
  6.  
  7. Disconnect the crankshaft position (CKP) sensor electrical connector.
  8.  
  9. Remove the CKP sensor bolt (1).
  10.  
  11. Remove the CKP sensor (2) from the engine block.
  12.  
  13. Remove the sensor by pulling on the sensor connector. DO NOT pry on the bracket.
  14.  
  15. DO NOT rotate or twist the sensor or damage the mounting bracket if the sensor is being reused.
  16.  

To install:

  1. Install and fully seat the CKP sensor (2) into the engine block.
  2.  
  3. Install the CKP sensor bolt. Tighten the bolt to 80 inch lbs. (9 Nm).
  4.  
  5. Ensure that the CKP sensor mounting flange is contacting the engine block.
  6.  
  7. Connect the CKP sensor electrical connector.
  8.  
  9. Install the starter motor.
  10.  
  11. Connect the negative battery cable.
  12.  
  13. Lower the vehicle.
  14.  
  15. Perform CKP System Variation Learn Procedure.
  16.  

3.8L
  1. Turn OFF the ignition.
  2.  
  3. Remove the serpentine belts from the crankshaft pulley.
  4.  
  5. Raise the vehicle.
  6.  
  7. Remove the right front wheel and tire assembly.
  8.  
  9. Remove the right inner fender access cover.
  10.  
  11. Hold the flywheel with a (J 37096) flywheel holding tool.
  12.  
  13. Using 28 mm socket, remove the crankshaft harmonic balancer retaining bolt.
  14.  
  15. Remove the crankshaft harmonic balancer, using a (J 38197-A) balancer remover.
  16.  
  17. Remove the crankshaft position sensor shield (1). Do not use a pry bar.
  18.  
  19. Disconnect the sensor electrical connector.
  20.  
  21. Remove the attaching bolts from the crankshaft position sensor.
  22.  
  23. Remove the crankshaft position sensor from the block face.
  24.  

To install:

  1. Position the crankshaft position (CKP) sensor to the block.
  2.  
  3. Install the bolts to hold the CKP sensor to the block face. Tighten the bolts to 14-28 ft. lbs. (20-40 Nm).
  4.  
  5. Reinstall the crankshaft position sensor shield.
  6.  
  7. Connect the CKP sensor electrical connector.
  8.  
  9. Position the crankshaft harmonic balancer on the crankshaft.
  10.  
  11. Hold the flywheel with a (J 37096) flywheel holding tool.
  12.  
  13. Using a (J 36660-A) torque/angle meter, tighten the harmonic balancer bolt to 110 ft. lbs. (150 Nm), plus an additional 76 degrees.
  14.  
  15. Install the right inner fender access cover.
  16.  
  17. Install the right front wheel and tire assembly.
  18.  
  19. Tighten the wheel nuts to 104 ft. lbs. (140 Nm.).
  20.  
  21. Lower the vehicle.
  22.  
  23. Reinstall the serpentine belts.
  24.  
  25. Perform the Crankshaft Variation Learn Procedure.
  26.  

 
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