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

Variable Camshaft Timing Oil Control Solenoid

Print

Operation



The CMP actuator assembly has an outer housing that is driven by an engine timing chain. Inside the assembly is a rotor with fixed vanes that is attached to the camshaft. Oil pressure that is applied to the fixed vanes will rotate a specific camshaft in relationship to the crankshaft. The movement of the intake camshafts will advance the intake valve timing up to a maximum of 50 crankshaft degrees. The movement of the exhaust camshafts will retard the exhaust valve timing up to a maximum of 50 crankshaft degrees. When oil pressure is applied to the return side of the vanes, the camshafts will return to 0 crankshaft degrees, or Top Dead Center (TDC). The CMP actuator solenoid valve directs the oil flow that controls the camshaft movement. The ECM commands the CMP solenoid to move the solenoid plunger and spool valve until oil flows from the advance passage. Oil flowing thru the CMP actuator assembly from the CMP solenoid advance passage applies pressure to the advance side of the vanes in the CMP actuator assembly. When the camshaft position is retarded, the CMP actuator solenoid valve directs oil to flow into the CMP actuator assembly from the retard passage. The ECM can also command the CMP actuator solenoid valve to stop oil flow from both passages in order to hold the current camshaft position.

The ECM operates the CMP actuator solenoid valve by Pulse Width Modulation (PWM) of the solenoid coil. The higher the PWM duty cycle, the larger the change in camshaft timing. The CMP actuator assembly also contains a lock pin that prevents movement between the outer housing and the rotor vane assembly. The lock pin is released by oil pressure before any movement in the CMP actuator assembly takes place. The ECM is continuously comparing CMP sensor inputs with CKP sensor input in order to monitor camshaft position and detect any system malfunctions. If a condition exists in either the intake or exhaust camshaft actuator system, the opposite bank, intake or exhaust, camshaft actuator will default to 0 crankshaft degrees

The camshaft actuator system enables the Engine Control Module (ECM) to change camshaft timing of all 4 camshafts while the engine is operating. The CMP actuator assembly varies the camshaft position in response to directional changes in oil pressure. The CMP actuator solenoid valve controls the oil pressure that is applied to advance or retard a camshaft. Modifying camshaft timing under changing engine demand provides better balance between the following performance concerns:



Engine power output
 
Fuel economy
 
Lower tailpipe emissions
 

Removal & Installation



2.8L & 3.6L Engines
Left Side (Exhaust) Bank 2
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Turn the ignition OFF.
    NOTE
    Do not disconnect the power steering fluid lines/hoses from the reservoir.

  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) actuator valve electrical connector.
  8.  
  9. Remove the CMP actuator valve bolt.
  10.  
  11. Remove the CMP actuator valve.
  12.  
  13. Inspect the CMP actuator valve seal for damage and replace as necessary.
  14.  

To install:

  1. Inspect the CMP actuator valve seal for damage. Replace the seal if necessary.
  2.  
  3. Install the CMP actuator valve.
  4.  
  5. Install the CMP actuator valve bolt.
  6.  
  7. Tighten the CMP actuator valve bolt to 89 inch lbs. (10 Nm).
  8.  
  9. Install the CMP actuator valve electrical connector.
  10.  
  11. Install the power steering fluid reservoir.
  12.  

Left Side (Intake) Bank 2
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Turn the ignition OFF.
    NOTE
    Do not disconnect the power steering fluid lines/hoses from the reservoir.

  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) actuator valve electrical connector.
  8.  
  9. Remove the CMP actuator valve bolt.
  10.  
  11. Remove the CMP actuator valve.
  12.  
  13. Inspect the CMP actuator valve seal for damage and replace as necessary.
  14.  

To install:

  1. Inspect the CMP actuator valve seal for damage. Replace the seal if necessary.
  2.  
  3. Install the CMP actuator valve.
  4.  
  5. Install the CMP actuator valve bolt.
  6.  
  7. Tighten the CMP actuator valve bolt to 89 inch lbs. (10 Nm).
  8.  
  9. Install the CMP actuator valve electrical connector.
  10.  
  11. Install the power steering fluid reservoir.
  12.  

Right Side (Exhaust) Bank 1
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Turn the ignition OFF.
  4.  
  5. Remove the Camshaft Position (CMP) actuator valve electrical connector.
  6.  
  7. Remove the CMP actuator valve bolt.
  8.  
  9. Remove the CMP actuator valve.
  10.  
  11. Inspect the CMP actuator valve seal and replace as necessary.
  12.  

To install:

  1. Inspect the CMP actuator valve seal for damage. Replace the seal if necessary.
  2.  
  3. Install the CMP actuator valve.
  4.  
  5. Install the CMP actuator valve bolt.
  6.  
  7. Tighten the CMP actuator valve bolt to 89 inch lbs. (10 Nm).
  8.  
  9. Install the CMP actuator valve electrical connector.
  10.  

Right Side (Intake) Bank 1
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Turn the ignition OFF.
    NOTE
    Do not remove the Engine Control Module (ECM) from the ECM bracket .

  4.  
  5. Remove the ECM bracket bolts and reposition the ECM bracket in order to provide access.
  6.  
  7. Remove the Camshaft Position (CMP) actuator valve electrical connector.
  8.  
  9. Remove the CMP actuator valve bolt.
  10.  
  11. Remove the CMP actuator valve.
  12.  
  13. Inspect the CMP actuator valve seal and replace as necessary.
  14.  

To install:

  1. Inspect the CMP actuator valve seal for damage. Replace the seal if necessary.
  2.  
  3. Install the CMP actuator valve.
  4.  
  5. Install the CMP actuator valve bolt.
  6.  
  7. Tighten the CMP actuator valve bolt to 89 inch lbs. (10 Nm).
  8.  
  9. Install the CMP actuator valve electrical connector.
  10.  
  11. Install the ECM bracket with the ECM.
  12.  

Testing



  1. Start the engine.
  2.  
  3. Allow the engine to reach operating temperature.
  4.  
  5. Increase the engine speed to 2,000 RPM for 10 seconds.
  6.  
  7. Observe the DTC information with a scan tool.
  8.  
  9. If DTC P0010, P0013, P0020, or P0023 failed this ignition.
  10.  
  11. Turn OFF the ignition.
  12.  
  13. Disconnect the Camshaft Position (CMP) actuator solenoid.
  14.  
  15. Turn ON the ignition, with the engine OFF.
  16.  
  17. Probe the ignition 1 voltage circuit of the CMP actuator solenoid with a test lamp that is connected to the Engine Control Module (ECM) housing.
  18.  
  19. The test lamp should illuminate, if not repair the ignition voltage circuit of the CMP actuator solenoid for an open or for an intermittent short to ground.
  20.  

 
label.common.footer.alt.autozoneLogo