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

Knock Sensor

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Operation



The Knock Sensor (KS) system detects engine knocking or pinging. The ECM will retard the spark timing based on the signals from the KS system. The KS produce an AC voltage that is sent to the Engine Control Module (ECM). The amount of the AC voltage produced is proportional to the amount of knock.

If knock occurs in any of the cylinders, the ignition will be retarded for that particular cylinder. If the knocking then stops, the ignition will be restored to what it was before in steps.

Should knocking continue in the same cylinder in spite of the ignition being retarded, the ECM will retard the ignition an additional steps, and so on, up to a maximum of 12 degrees of retard. The ignition will also be retarded at high ambient temperatures in order to counteract knocking tendencies provoked by high intake air temperatures.

Should either bank 1 or bank 2 sensor fail to work, or should an internal circuit problem occur, the ignition timing will then use a default strategy. The default strategy will retard the ignition the maximum allowed amount to protect the engine from possible damage.

Removal & Installation



2.8L & 3.6L Engines
Bank 1
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Turn the ignition OFF.
  4.  
  5. Raise and support the vehicle.
  6.  
  7. Reposition the wiring harness heat shield to obtain access.
  8.  
  9. Remove the Knock Sensor (KS) electrical connector.
  10.  
  11. Remove the KS bolt.
  12.  
  13. Remove the KS.

    Click image to see an enlarged view

    Fig. Knock Sensor (KS) removal bank 1

  14.  

To install:

  1. Install the KS.
  2.  
  3. Tighten the KS bolt to 17 ft. lbs. (23 Nm).
  4.  
  5. Install the KS electrical connector.
  6.  
  7. Install the wiring harness heat shield to the original position.
  8.  
  9. Lower the vehicle.
  10.  

Bank 2
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Turn the ignition OFF.
  4.  
  5. Raise and support the vehicle.
  6.  
  7. Remove the wiring harness heat shield from the oil level indicator tube to gain access.
  8.  
  9. Remove the Knock Sensor (KS) electrical connector.
  10.  
  11. Remove the KS bolt.
  12.  
  13. Remove the KS.
  14.  

To install:

  1. Install the KS.
  2.  
  3. Install the KS bolt.
  4.  
  5. Tighten the KS bolt to 17 ft. lbs. (23 Nm).
  6.  
  7. Install the KS electrical connector.
  8.  
  9. Install the wiring harness heat shield to the oil level indicator tube .
  10.  
  11. Lower the vehicle.
  12.  

4.6L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the intake manifold.
  4.  
  5. Disconnect the electrical connector from the right knock sensor, if required.
  6.  
  7. Disconnect the electrical connector from the left knock sensor, if required.
  8.  
  9. Remove the appropriate knock sensor.

    Click image to see an enlarged view

    Fig. Knock Sensors (KS) removal 4.6L

  10.  

To install:

  1. Install the appropriate knock sensor.
  2.  
  3. Tighten the sensor to 18 ft. lbs. (25 Nm).
  4.  
  5. Connect the electrical connector to the left knock sensor, if required.
  6.  
  7. Connect the electrical connector to the right knock sensor, if required.
  8.  
  9. Install the intake manifold.
  10.  

5.7L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the intake manifold.
  4.  
  5. Remove the knock sensor wiring harness assembly.
  6.  
  7. Remove the knock sensor.

    Click image to see an enlarged view

    Fig. Knock Sensors (KS) removal 5.7L

  8.  

To install:

  1. Install the knock sensor.
  2.  
  3. Tighten the knock sensor to 15 ft. lbs. (20 Nm).
  4.  
  5. Install the knock sensor wiring harness assembly.
  6.  
  7. Install the intake manifold.
  8.  
  9. Connect the negative battery cable.
  10.  

6.0L Engine
Bank 1
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Raise the vehicle.
  4.  
  5. Disconnect the knock sensor electrical connector.
  6.  
  7. Remove the knock sensor mounting bolt.
  8.  
  9. Remove the knock sensor.
  10.  

To install:

  1. Position the knock sensor to the engine block.
  2.  
  3. Install the knock sensor mounting bolt.
  4.  
  5. Tighten the knock sensor mounting bolt to 15 ft. lbs. (20 Nm).
  6.  
  7. Connect the knock sensor electrical connector.
  8.  
  9. Lower the vehicle.
  10.  

Bank 2
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Raise the vehicle.
  4.  
  5. Disconnect the knock sensor electrical connector.
  6.  
  7. Remove the knock sensor mounting bolt.
  8.  
  9. Remove the knock sensor.

    Click image to see an enlarged view

    Fig. Knock Sensors (KS) removal bank 2

  10.  

To install:

  1. Position the knock sensor to the engine.
  2.  
  3. Install the knock sensor mounting bolt.
  4.  
  5. Tighten the knock sensor mounting bolt 1 to 15 ft. lbs. (20 Nm).
  6.  
  7. Connect the knock sensor electrical connector.
  8.  
  9. Lower the vehicle.
  10.  

Testing



  1. Connect a Digital Multi-Meter (DMM) to both KS signal circuit terminals A and B or 1 and 2 at the Knock Sensor (KS).
  2.  
  3. Set the DMM to the 400 mV AC hertz scale and wait for the DMM display to stabilize at 0 Hz.
  4.  
  5. Tap on the engine block with a non-metallic object near the KS while observing the signal indicated on the DMM.
  6.  
  7. The DMM should display a fluctuating frequency while tapping on the engine block.
  8.  
  9. If no fluctuating frequency was displayed with the DMM, replace the faulty KS sensor.
  10.  

 
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