GM Corsica/Beretta 1988-1996 Repair Guide

Crankshaft Position (CKP) Sensor

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OPERATION



The CKP sensor provides a signal through the ignition module which the PCM uses as a reference to calculate RPM and crankshaft position.

TESTING



The best method to test this sensor is with the use of an oscilloscope.

2.0L and 2.2L Engines
1988-95 VEHICLES

See Figure 1

  1. Visually check the connector, making sure it is connected properly and all of the terminals are straight, tight and free of corrosion.
  2.  
  3. Connect a suitable scan tool to the Data Link Connector (DLC), set the scan tool to check for a rpm signal or the CKP sensor reference pulse. Crank the engine briefly while observing the readings on the scan tool:
    1. If the scan tool registers a rpm reading or has a steady reference pulse from the CKP sensor, the sensor is operating normally.
    2.  
    3. If the rpm reading or reference pulse is erratic, proceed to the next step.
    4.  
    5. If there is no rpm reading or reference pulse, proceed to the next step.
    6.  

  4.  
  5. Turn the ignition switch to the OFF position, then detach the connector from the CKP sensor.
  6.  



Click image to see an enlarged view

Fig. Fig. 1: Crankshaft Position (CKP) sensor circuits - 2.0L and 2.2L engines

  1. Connect a test light between a known good engine ground and terminal C, at the CKP sensor connector:
    1. If the test light illuminates, proceed to the next step.
    2.  
    3. If the test light does not illuminate, check the CKP sensor feed circuit.
    4.  

  2.  
  3. Turn the ignition switch to the OFF position.
  4.  
  5. Connect the test light to the positive battery terminal.
  6.  
  7. Connect the test light to terminal B of the CKP sensor connector:
    1. If the test light illuminates, proceed to the next step.
    2.  
    3. If the test light does not illuminate, check the CKP sensor ground circuit.
    4.  

  8.  
  9. With the scan tool connected to the DLC, turn the ignition switch to the ON position.
  10.  
  11. With the test light, touch terminal B at the CKP sensor connector, while observing the scan tool for a reference pulse change.
    1. If the reference pulse changes (or increments), replace the CKP sensor.
    2.  
    3. If the reference pulse does not change, check the reference signal circuit.
    4.  

  12.  

1996 VEHICLES

See Figure 1

The CKP sensor used on these vehicles is a three-wire, Hall effect type sensor. The sensor requires power and ground to function. When performing this test, backprobe all connectors.

  1. Visually check the connector, making sure it is connected properly and all of the terminals are straight, tight and free of corrosion.
  2.  
  3. With the ignition in the ON position, check the sensor voltage using an oscilloscope. When the starter is briefly operated a square wave pattern, varying between 0-12 volts should be seen at terminal A.
  4.  
  5. If the voltage falls out of range, use a DVOM to check terminal C for battery positive (B+). If battery positive (B+) is not present, check the circuit continuity and repair as necessary.
  6.  
  7. If battery positive (B+) is found at terminal C, check the terminal B for proper ground. If ground is not present, check the circuit for continuity and repair as necessary.
  8.  
  9. If the sensor and circuits are functional, the PCM may be faulty.
  10.  

2.3L Engine

See Figure 2

  1. Visually check the connector, making sure it is connected properly and all of the terminals are straight, tight and free of corrosion.
  2.  
  3. Connect a suitable scan tool to the Data Link Connector (DLC), set the scan tool to check for a rpm signal or the CKP sensor reference pulse. Crank the engine briefly while observing the readings on the scan tool:
    1. If the scan tool registers a rpm reading or has a steady reference pulse from the CKP sensor, the sensor is operating normally.
    2.  
    3. If the rpm reading or reference pulse is erratic, proceed to the next step.
    4.  
    5. If there is no rpm reading or reference pulse, proceed to the next step.
    6.  

  4.  
  5. Turn the ignition switch to the OFF position, then detach the connector from the CKP sensor.
  6.  



Click image to see an enlarged view

Fig. Fig. 2: Crankshaft Position (CKP) sensor circuits - 2.3L engines

  1. Connect a test light between the CKP sensor terminals A and B, then briefly operate the starter motor while watching the voltmeter:
    1. If the voltage is greater than 0.2 volts, proceed to the next step.
    2.  
    3. If the voltage is 0.2 volts AC or less, replace the CKP sensor.
    4.  

  2.  
  3. Remove the CKP sensor from the engine.
  4.  
  5. Check the resistance between terminals A and B:
    1. If the resistance is between 500-900 ohms, proceed to the next step.
    2.  
    3. If the resistance is below 500 ohms or above 900 ohms, replace the CKP sensor.
    4.  

  6.  
  7. Verify that the CKP sensor is still magnetic:
    1. If the sensor is magnetic, the sensor is good.
    2.  
    3. If the CKP sensor is not magnetic, replace the sensor.
    4.  

  8.  

2.8L and 3.1L (VIN T) Engines

See Figure 3

  1. Visually check the connector, making sure it is connected properly and all of the terminals are straight, tight and free of corrosion.
  2.  
  3. Connect a suitable scan tool to the Data Link Connector (DLC), set the scan tool to check for a rpm signal or the CKP sensor reference pulse. Crank the engine briefly while observing the readings on the scan tool:
    1. If the scan tool registers a rpm reading or has a steady reference pulse from the CKP sensor, the sensor is operating normally.
    2.  
    3. If the rpm reading or reference pulse is erratic, proceed to the next step.
    4.  
    5. If there is no rpm reading or reference pulse, proceed to the next step.
    6.  

  4.  
  5. Turn the ignition switch to the OFF position, then detach the 2-wire connector from the ignition module.
  6.  



Click image to see an enlarged view

Fig. Fig. 3: Crankshaft Position (CKP) sensor circuits - 2.8L and 3.1L (VIN T) engines

  1. Turn the ignition to the ON position.
  2.  
  3. Connect a test light between a known good engine ground and terminal A of the 2-wire ignition module connector:
    1. If the test light illuminates, proceed to the next step.
    2.  
    3. If the test light does not illuminate, check the power supply circuit.
    4.  

  4.  
  5. Turn the ignition switch to the OFF position.
  6.  
  7. Connect the test light to the positive battery terminal.
  8.  
  9. Connect the test light to terminal B of the 2-wire ignition module connector:
    1. If the test light illuminates, proceed to the next step.
    2.  
    3. If the test light does not illuminate, check the ignition module ground circuit.
    4.  

  10.  
  11. Disconnect the connector from the CKP sensor.
  12.  
  13. Check the resistance between terminals A and B of the CKP sensor:
    1. If the resistance is between 900-1200 ohms, proceed to the next step.
    2.  
    3. If the resistance is below 900 ohms or above 1200 ohms, replace the CKP sensor.
    4.  

  14.  
  15. Connect a voltmeter between the CKP sensor terminals A and B, then briefly operate the starter motor while watching the voltmeter:
    1. If the voltage is greater than 0.1 volt AC, the CKP sensor is operating properly.
    2.  
    3. If the voltage is 0.1 volt AC or less, replace the CKP sensor.
    4.  

  16.  

REMOVAL & INSTALLATION



See Figure 4

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the harness connector at the crankshaft sensor.
  4.  
  5. Remove the sensor attaching bolt.
  6.  
  7. Remove the crankshaft sensor from the engine.
  8.  
  9. Inspect the sensor O-ring for wear, cracks or signs of leakage. Replace it if necessary.
  10.  



Click image to see an enlarged view

Fig. Fig. 4: Location of the Crankshaft Position (CKP) sensor - 2.3L engine

To install:
  1. Lubricate the O-ring with engine oil and install it on the sensor.
  2.  
  3. Position the sensor to the engine block and install the attaching bolt. Tighten the attaching bolt to 71-88 inch lbs. (8-10 Nm).
  4.  
  5. Connect the sensor harness connector.
  6.  
  7. Connect the negative battery cable.
  8.  
  9. Start the engine and test engine performance.
  10.  

 
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