CTS 2006-2007, CTS-V 2005-2007, DTS 2006-2007

Camshaft Position Sensor

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Description & Operation



2.8L & 3.6L Engines

This engine uses 4 Camshaft Position (CMP) sensors, one for each camshaft. The CMP sensor signals are a digital ON/OFF pulse, output 4 times per revolution of the camshaft. The CMP sensor does not directly affect the operation of the ignition system. The CMP sensor information is used by the Engine Control Module (ECM) to determine the position of the 4 camshafts relative to the crankshaft position. By monitoring the CMP and Crankshaft Position (CKP) signals the ECM can accurately time the operation of the fuel injectors. The ECM supplies the CMP sensor with a 5-volt reference circuit and a low reference circuit. The CMP sensor signals are an input to the ECM. These signals are also used to detect camshaft alignment with the crankshaft.

4.6L Engine

The camshaft position (CMP) sensor is triggered by a notched reluctor wheel built onto the exhaust camshaft sprocket. The CMP sensor provides four signal pulses every camshaft revolution. Each notch, or feature of the reluctor wheel is of a different size which is used to identify the compression stroke of each cylinder and to enable sequential fuel injection. The CMP sensor is connected to the Engine Control Module (ECM) by the following circuits:



A 5-volt reference circuit
 
A low reference circuit
 
A signal circuit
 

5.7L Engine

The Camshaft Position (CMP) sensor is a magneto resistive sensor, with the same type of circuits as the CKP sensor. The CMP sensor signal is a digital ON/OFF pulse, output once per revolution of the camshaft. The CMP sensor information is used by the PCM to determine the position of the valve train relative to the CKP.

6.0L Engine

The Camshaft Position (CMP) sensor is a 3-wire sensor that provides a digital output signal. The wire circuits consist of an Engine Control Module (ECM) supplied 5-volt reference circuit, a low reference circuit between the CMP sensor and the ECM, and an output signal circuit from the CMP sensor to the ECM. The CMP sensor detects magnetic flux changes between the teeth and slots on the 4-tooth reluctor wheel. The CMP sensor provides a digital ON/OFF DC voltage of varying frequency, with 4 varying width output pulses, per each camshaft revolution. The frequency of the CMP sensor output signal depends on the speed of the camshaft. The ECM will recognize the narrow and wide tooth patterns to identify camshaft position, or which cylinder is in compression and which is in exhaust. The information is then used to determine the correct time and sequence for fuel injection and ignition spark events. The ECM also uses the CMP sensor output signal to determine the camshaft relative position to the crankshaft position.

Removal & Installation



2.8L & 3.6L Engines
Left Bank 2 Exhaust & Intake
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Turn the ignition OFF.
  4.  
  5. Remove the power steering fluid reservoir bolts and reposition the power steering fluid reservoir in order to provide access.
  6.  
  7. Remove the Camshaft Position (CMP) sensor electrical connector.
  8.  
  9. Remove the CMP sensor bolt.
  10.  
  11. Remove the CMP sensor.
  12.  

To install:

  1. Install the CMP sensor.
  2.  
  3. Install the CMP sensor bolt.
  4.  
  5. Tighten the CMP sensor bolt to 89 inch lbs. (10 Nm).
  6.  
  7. Install the CMP sensor electrical connector.
  8.  
  9. Install the power steering fluid reservoir.
  10.  

Right Bank 1 Exhaust & Intake
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Turn the ignition OFF.
  4.  
  5. Remove the ECM bracket bolts and reposition the ECM bracket in order to provide access.
  6.  
  7. Remove the Camshaft Position (CMP) sensor electrical connector.
  8.  
  9. Remove the CMP sensor bolt.
  10.  
  11. Remove the CMP sensor.
  12.  

To install:

  1. Install the CMP sensor.
  2.  
  3. Install the CMP sensor bolt.
  4.  
  5. Tighten the CMP sensor bolt to 89 inch lbs. (10 Nm).
  6.  
  7. Install the CMP sensor electrical connector.
  8.  
  9. Install the ECM bracket with the ECM.
  10.  

4.6L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Disconnect the electrical connector from the Camshaft Position (CMP) sensor.
  4.  
  5. Remove the CMP sensor bolt.
  6.  
  7. Remove the CMP sensor.

    Click image to see an enlarged view

    Fig. Camshaft Position (CMP) sensor removal 4.6L

  8.  

To install:

  1. Lubricate the CMP sensor O-ring seal with clean engine oil.
  2.  
  3. Install the CMP sensor.
  4.  
  5. Install the CMP sensor bolt.
  6.  
  7. Tighten the CMP sensor bolt to 89 inch lbs. (10 Nm). Connect the electrical connector to the CMP sensor.
  8.  

5.7L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Remove the intake manifold.
  6.  
  7. Remove the Camshaft Position (CMP) sensor electrical connector.
    NOTE
    Clean the area around the CMP before removal in order to avoid debris from entering the engine.

  8.  
  9. Remove the CMP sensor retaining bolt.
  10.  
  11. Remove the CMP sensor.
  12.  

To install:

  1. Install the CMP sensor.
  2.  
  3. Install the CMP sensor retaining bolt. Tighten the CMP to 18 ft. lbs. (25 Nm).
  4.  
  5. Connect the CMP sensor electrical connector.
  6.  
  7. Install the intake manifold.
  8.  
  9. Connect the negative battery cable.
  10.  

6.0L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the accessory drive belt.
  4.  
  5. Remove the air conditioning drive belt.
  6.  
  7. Remove the accessory drive belt idler pulley.
  8.  
  9. Remove the crankshaft balancer assembly.
  10.  
  11. Remove the camshaft position sensor mounting bolts.
  12.  
  13. Remove the camshaft position sensor assembly (4, 5, 6) from the front cover (7).
  14.  
  15. Disconnect the camshaft position sensor jumper harness (2) and the engine harness (3) electrical connectors.
  16.  
  17. Remove the camshaft sensor assembly (4, 5, 6).
  18.  
  19. Disconnect the camshaft position sensor (5) from the jumper harness (4).

    Click image to see an enlarged view

    Fig. 6.0L Camshaft Position (CMP) Sensor and related parts

  20.  

To install:

  1. Reconnect the camshaft sensor (5) and the jumper harness (4).
  2.  
  3. Install the O-ring (6) on the camshaft sensor assembly (4 and 5).
  4.  
  5. Reconnect the camshaft position sensor assembly (4, 5 and 6) and the engine harness connector (3).
  6.  
  7. Install the camshaft position sensor assembly (4, 5 and 6) in the front cover (7).
  8.  
  9. Install the camshaft position sensor mounting bolts.
  10.  
  11. Tighten the camshaft position mounting bolts 18 ft. lbs. (25 Nm).
  12.  
  13. Install the crankshaft balancer assembly.
  14.  
  15. Install the accessory drive belt idler pulley.
  16.  
  17. Install the air conditioning drive belt.
  18.  
  19. Install the accessory drive belt.
  20.  

Testing



2.8L, 3.6L, 4.6L & 6.0L Engines
  1. Inspect the CMP sensor for correct installation. Remove the CMP sensor from the engine and inspect the sensor O-ring for damage.
  2.  
  3. If the sensor is loose, incorrectly installed, or damaged, replace the CMP sensor.
  4.  
  5. Connect the CMP sensor harness connector to the CMP sensor.
  6.  
  7. Ignition ON, engine OFF. Observe the CMP Active counter parameter on the scan tool.
  8.  
  9. Pass a flat steel object across the tip of the sensor repeatedly. The CMP Active counter parameter should increment with each pass of the steel object.
  10.  
  11. If the parameter does not increment, replace the CMP sensor.
  12.  

5.7L Engine
  1. Remove the CMP sensor.
  2.  
  3. Visually inspect the CMP sensor for the following conditions:

    Physical damage
     
    Excessive wear of the sensor
     
    Loose or improper installation
     
    The sensor coming in contact with the reluctor ring
     
    Foreign material passing between the sensor and the reluctor ring
     
    Wiring routed too close to secondary ignition components
     

  4.  
  5. Visually inspect the CMP sensor reluctor ring for the following conditions:

    Physical damage
     
    Excessive end play or looseness
     
    Loose or improper installation
     

  6.  
  7. Disconnect the CMP sensor.
  8.  
  9. Turn ON the ignition, with the engine OFF.
  10.  
  11. Check harness connector pin (C) for voltage reference.
  12.  
  13. If no voltage reference, check for an open circuit.
  14.  

 
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