GM Camaro/Firebird 1993-1998 Repair Guide

Crankshaft Position (CKP) Sensor

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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.

3.8L Engine

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. 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 and providing 3 pulses per crankshaft revolution should be seen at terminal V. The same signal providing 18 pulses per crankshaft revolution should be seen at terminal A. If voltage is within specification, the sensor is functional.
  4.  



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Fig. Fig. 1: Crankshaft Position (CKP) sensor circuit-3.8L engine

  1. 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.
  2.  
  3. If battery positive (B+) is found at terminal C, check the terminal D for proper ground. If ground is not present, check the circuit for continuity and repair as necessary.
  4.  
  5. If the sensor and circuits are functional, the PCM may be faulty.
  6.  

5.7L 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. If a Tech 1® or equivalent scan tool is available, scan the CKP or RPM parameter while cranking the engine. If signals are indicated, the CKP sensor is functioning properly.
  4.  
  5. If the scan tool is not available, use a voltmeter set to the DC voltage range to test the sensor.
  6.  
  7. Backprobe the sensor connector and check for system voltage at terminal D and ground at terminal C.
  8.  



Click image to see an enlarged view

Fig. Fig. 2: Crankshaft Position (CKP) sensor circuit-5.7L engine

  1. Crank the engine over slowly while backprobing the crankshaft sensor connector terminal A and ground. This is the 18X signal line. The voltage reading should vary between 0 volts and system voltage (usually 8-12 volts) 18 times per crankshaft revolution.
  2.  
  3. Crank the engine over slowly while backprobing the crankshaft sensor connector terminal B and ground. This is the 3X signal line. The voltage reading should vary between 0 volts and system voltage (usually 8-12 volts) 3 times per crankshaft revolution.
  4.  
  5. If this varying voltage is not seen, check circuits for continuity and repair as necessary.
  6.  
  7. If the sensor and circuits are functional, the PCM may be faulty.
  8.  

REMOVAL & INSTALLATION



3.8L Engine

See Figures 3 and 4

  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. Remove the crankshaft balancer.
  6.  
  7. Remove the fuel pump/engine oil pressure sensor wire harness retainer clip from the shield.
  8.  
  9. Detach the electrical connector from the crankshaft position sensor.
  10.  
  11. Remove the crankshaft position sensor shield and studs, then remove the crankshaft position sensor from the engine front cover. Inspect the sensor O-ring for wear, cracks or damage and replace if necessary.
  12.  



Click image to see an enlarged view

Fig. Fig. 3: Exploded view of the crankshaft position sensor shield-3.8L engine



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Fig. Fig. 4: The crankshaft position sensor on the 3.8L engine is secured with two studs

To install:
  1. Lubricate the sensor O-ring with clean engine oil. Position the sensor to the engine front cover and install the retaining studs. Tighten the studs to 16 ft. lbs. (20 Nm), plus an additional 40 degree turn.
  2.  
  3. Install the crankshaft position sensor shield.
  4.  
  5. Attach the electrical connector to the crankshaft position sensor.
  6.  
  7. Fasten the fuel pump/engine oil pressure sensor wire harness retainer clip to the shield.
  8.  
  9. Install the crankshaft balancer.
  10.  
  11. Install the serpentine drive belt.
  12.  
  13. Connect the negative battery cable.
  14.  

5.7L Engine
1993-97 VEHICLES

See Figure 5

  1. Disconnect the negative battery cable.
  2.  
  3. Raise and safely support the vehicle.
  4.  
  5. Detach the CKP sensor electrical connector.
  6.  
  7. Unfasten the CKP sensor retaining screw, then remove the sensor from the vehicle.
  8.  



Click image to see an enlarged view

Fig. Fig. 5: Crankshaft Position (CKP) sensor mounting-1993-97 5.7L engines

To install:
  1. Position the CKP sensor and install the retaining screw. Tighten the screw to 35-53 inch lbs. (4-6 Nm).
  2.  
  3. Attach the sensor electrical connector.
  4.  
  5. Carefully lower the vehicle, then connect the negative battery cable.
  6.  

1998 VEHICLES

See Figures 6, 7 and 8

Antime the CKP sensor is removed or replaced, you must perform a CKP system variation learn procedure, which requires the use of a Tech 1® or equivalent scan tool.

  1. Disconnect the negative battery cable.
  2.  
  3. Raise and safely support the vehicle.
  4.  
  5. Remove the starter, as outlined in Engine Electrical of this repair guide.
  6.  



Click image to see an enlarged view

Fig. Fig. 6: For access to the CKP sensor, remove the starter from the vehicle

  1. Detach the CKP sensor electrical connector.
  2.  



Click image to see an enlarged view

Fig. Fig. 7: Unplug the CKP sensor electrical connector

  1. Remove the CKP sensor retaining bolt, then remove the sensor from the vehicle.
  2.  



Click image to see an enlarged view

Fig. Fig. 8: Remove the retaining bolt, then remove the CKP sensor from the vehicle

To install:
  1. Install the CKP sensor and secure with the retaining bolt. Tighten the bolt to 18 ft. lbs. (25 Nm).
  2.  
  3. Attach the CKP electrical connector.
  4.  
  5. Install the starter, as outlined in Engine Electrical of this repair guide.
  6.  
  7. Carefully lower the vehicle, then connect the negative battery cable.
  8.  
  9. Perform the CKP system variation learn procedure, as follows:
  10.  

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 will respond to throttle position after the learn procedure is complete.

    1. Install a Tech 1® or equivalent scan tool.
    2.  
    3. Apply the parking brake and block the drive wheels.
    4.  
    5. Close the vehicle's hood. Start the engine.
    6.  
    7. Place the transmission in P (A/T) or N (M/T).
    8.  
    9. Idle the engine until the coolant temperature reaches 150°F (65°C).
    10.  
    11. Turn OFF all of the accessories.
    12.  
    13. Apply the brakes for the duration of the procedure.
    14.  
    15. Enable the Crankshaft Position System Variation Learn procedure with the scan tool.
    16.  
    17. Slowly raise the engine speed to 4000 RPM.
    18.  
    19. Immediately release the throttle when the engine speed decreases.
    20.  
    21. After the learn procedure is completed, turn the engine OFF for 15 seconds.
    22.  


 
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