GM Corsica/Beretta 1988-1996 Repair Guide

3X Signal Crankshaft Position (CKP) Sensor

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OPERATION



The 3x Crankshaft Position (CKP) sensor, used on 1994-95 3.1L (VIN M) engines, provides a signal to the PCM through the ignition control module. The PCM uses this signal to determine RPM and crankshaft position.

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 sine wave pattern, alternating from high voltage to low voltage should be seen. If the voltage is less than 0.1 volt the sensor is faulty.
  4.  



Click image to see an enlarged view

Fig. Fig. 1: Crankshaft Position (CKP) sensor circuits - 3.1L (VIN M) engine

  1. If the voltage is within specification, check the resistance at the CKP terminals. If the resistance is not between 900-1200 ohms, the sensor is faulty.
  2.  
  3. If the signal and resistance of the CKP sensor are within specifications, use a DVOM to check for continuity (short, open or high resistance greater than 0.50 ohms) in the CKP circuit wires and repair as necessary.
  4.  
  5. If the sensor and circuits are functional, the computer control module may be faulty.
  6.  

REMOVAL & INSTALLATION



3.1L (VIN M) Engine
1994-95 VEHICLES

See Figure 2

  1. Turn the steering wheel all the way to the left.
  2.  
  3. Be sure the ignition is in the OFF or LOCK position, then disconnect the negative battery cable.
  4.  
  5. Raise and safely support the vehicle.
  6.  
  7. Disengage the wiring harness connector from the sensor.
  8.  
  9. Remove the sensor retaining bolt, then carefully remove the sensor from the lower right side of the engine block.
  10.  



Click image to see an enlarged view

Fig. Fig. 2: 3X Crankshaft Position (CKP) sensor mounting - 1994-95 3.1L engine

To install:
  1. Inspect the sensor O-ring and replace, if necessary.
  2.  
  3. Lubricate the O-ring with clean engine oil, then install the sensor into the hole in the side of the engine block.
  4.  
  5. Install the sensor retaining bolt and tighten to 71 inch lbs. (8 Nm).
  6.  
  7. Engage the sensor wiring harness at the module.
  8.  
  9. Carefully lower the vehicle, then connect the negative battery cable.
  10.  
  11. Turn the steering wheel back to its original position.
  12.  

 
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