GM Malibu/Cutlass 1997-2000

Camshaft Position (CMP) Sensor

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OPERATION



The PCM uses the Camshaft Position (CMP) sensor signal to determine the position of the No. 1 cylinder piston during its power stroke. The signal is used by the PCM to calculate fuel injection mode of operation.

If the cam signal is lost while the engine is running, the fuel injection system will shift to a calculated fuel injected mode based on the last fuel injection pulse, and the engine will continue to run.

TESTING



  1. Remove the PCM fuse to prevent the engine from starting. Removal of the PCM fuse does not disable the sensor power supply and allows testing of this sensor safely.
  2.  
  3. Disconnect the CMP sensor wiring harness and attach suitable jumper wires between the CMP sensor and CMP sensor harness. Connect a DC voltmeter to the jumper wires corresponding to CMP IGN or PWR terminal and sensor ground.
  4.  
  5. With the ignition ON and the engine OFF , verify that the voltage is approximately battery voltage. The supply voltage should be slightly less than battery voltage.
  6.  
  7. If not as specified, repair or replace the fuse and/or wiring.
  8.  
  9. Connect a DC voltmeter to the jumper wires corresponding to CMP signal terminal and sensor ground.
  10.  
  11. Place a socket and breaker bar or the crankshaft pulley bolt and rotate the engine slowly by hand. Observe the voltmeter and verify that the voltage signal varies from approximately zero volts to slightly less than supply voltage. The voltage will switch on when the target passes the sensor and will show little or no voltage when the target is past the sensor.
  12.  
  13. If it is not as specified, the CMP sensor may be faulty.
  14.  

REMOVAL & INSTALLATION



  1. Disconnect the negative battery cable.
  2.  
  3. Unplug the CMP sensor harness connector from the sensor.
  4.  



Click image to see an enlarged view

Fig. Unplug the sensor harness connector (1) from the CMP sensor-2.4L engine shown



Click image to see an enlarged view

Fig. Unfasten the retaining bolt, then remove the CMP sensor from the camshaft housing-3.1L engine shown

  1. Unfasten the retaining bolt, then remove the sensor from the camshaft housing.
  2.  

To install:

  1. Place the sensor into position.
  2.  
  3. Install the CMP sensor retaining bolt, then tighten to 88 inch lbs. (10 Nm).
  4.  
  5. Attach the sensor harness connector.
  6.  
  7. Connect the negative battery cable.
  8.  

 
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