ION, L-Series, S-Series 1999-2005

Camshaft Position Sensor

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Description & Operation



The PCM uses the Camshaft Position (CMP) sensor to determine the position of the No. 1 piston during its power stroke. This 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.

Removal & Installation



  1. Disconnect the negative battery cable.
  2.  
  3. Remove the drive belt tensioner.
  4.  
  5. Remove the underhood junction block.
  6.  
  7. Disconnect the electrical connector from the Camshaft Position (CMP) sensor.
  8.  
  9. Remove the CMP sensor studs.
  10.  
  11. Remove the CMP sensor.
  12.  

To install:

  1. Rotate the crankshaft until number 4 piston is at top dead center (TDC) on the compression stroke.
  2.  
  3. Install the NEW camshaft position sensor housing seal.
  4.  
  5. Align the timing mark on the housing with the timing mark on the hex shaft.
  6.  
  7. Install the camshaft position sensor housing.
  8.  
  9. Install the camshaft position sensor housing studs and tighten to 16 ft. lbs. (22 Nm).
  10.  
  11. Install the underhood junction block.
  12.  
  13. Install the drive belt tensioner.
  14.  
  15. Connect the negative battery cable.

    Click image to see an enlarged view

    Fig. Rotate the crankshaft until number 4 piston is at top dead center (TDC) on the compression stroke before installing the new Camshaft Position (CMP) sensor

  16.  

Testing



  1. Check the condition of the connector. Make sure the connector is firmly attached. Check for broken or bent connector pins. Repair any connector damage before continuing with troubleshooting the issue.
  2.  
  3. Check the condition of the wiring to the connector. If the wiring is damaged, repair the wiring before continuing with any further tests.
  4.  
  5. Visually inspect the CMP sensor reluctor ring for damage, repair as needed.
  6.  
  7. Measure the voltage from the 5-volt reference circuit of the CMP sensor to a good ground. The voltage should be 5 volts. If not check the wiring for an open or short.
  8.  
  9. Measure the resistance of the low reference circuit of the CMP sensor. The resistance should be 5 ohms. If the resistance is not as specified, check the low reference circuit of the CMP sensor for an open or high resistance.
  10.  
  11. Measure the resistance of the 5-volt reference circuit of the CMP sensor The resistance should be 5 ohms. If the resistance is not as specified, check the 5-volt reference circuit of the CMP sensor for an open or high resistance.
  12.  
  13. If there are no issues with the wiring and connectors, replace the sensor.

    Click image to see an enlarged view

    Fig. Camshaft Position (CMP) sensor terminals; (1) 5 volt reference, (3) Low reference

  14.  

 
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