GM Corsica/Beretta 1988-1996 Repair Guide

24X Signal Crankshaft Position (CKP) Sensor

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OPERATION



The 24X CKP sensor is used to improve the idle spark control at engine speeds up to approximately 2000 RPM.

TESTING



See Figure 1

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

  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, alternating between 0-12 volts should be seen at terminal B. If the voltage is within specification, the sensor is functional.
  4.  
  5. If the voltage falls out of range, use a DVOM to check terminal A 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 A, check the terminal C 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.  

REMOVAL & INSTALLATION



3.1L (VIN M) Engine

See Figures 2 and 3

  1. Be sure the ignition is in the OFF or LOCK position, then disconnect the negative battery cable.
  2.  
  3. Remove the serpentine belt from the crankshaft pulley.
  4.  
  5. Raise and support the vehicle safely.
  6.  
  7. Remove the crankshaft harmonic balancer assembly from the front of the engine, as follows:
    1. Remove the bolt and washer from the crankshaft harmonic balancer.
    2.  
    3. Remove the retaining bolts from the crankshaft pulley, then remove the pulley from the balancer.
    4.  
    5. Using J-24420-B or an equivalent torsional damper remover, pull the balancer from the crankshaft.Note the routing of the CKP sensor harness before removal.
    6.  

  8.  
  9. Remove the harness retaining clip with the bolt. Detach the sensor harness connector.
  10.  
  11. Remove the sensor retaining bolts, then remove the sensor from the engine.
  12.  



Click image to see an enlarged view

Fig. Fig. 1: The 24X CKP sensor, found on 3.1L (VIN M) engines, is mounted to the timing chain (front) cover



Click image to see an enlarged view

Fig. Fig. 2: Exploded view of the 24X CKP sensor - 1994-95 3.1L engines



Click image to see an enlarged view

Fig. Fig. 3: 24X Crankshaft Position (CKP) sensor mounting - 1996 3.1L engines

To install:
  1. Install the sensor to the engine and tighten the retaining bolts to 8 ft. lbs. (10 Nm).
  2.  
  3. Route the harness as noted during removal, then install the harness retaining clip and secure with the bolt. Tighten the bolt to 8 ft. lbs. (10 Nm).
  4.  
  5. Attach the sensor electrical connector.
  6.  
  7. Use J-29113, or an equivalent installer, to pull the balancer onto the crankshaft. Install the crankshaft balancer bolt and tighten it to 110 ft. lbs. (150 Nm).
  8.  
  9. Install and tighten the crankshaft pulley bolts.
  10.  
  11. Install the serpentine drive belt.
  12.  
  13. Carefully lower the vehicle.
  14.  
  15. Connect the negative battery cable.
  16.  

 
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