Silverado 2008

Knock Sensor (KS)

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Location



Specific to:

Chevrolet Silverado 1500 2008

The Knock Sensor (KS) sensor is located on the sides of the engine block.

Operation



Specific to:

Chevrolet Silverado 1500 2008

The knock sensor system enables the PCM to control ignition timing for best performance while protecting the engine from detonation.

The KS system uses one or 2 flat response 2-wire sensors. The sensor uses piezo-electric crystal technology that produces an AC voltage signal of varying amplitude and frequency based on the engine vibration or noise level. The control module receives the KS signal through a signal circuit. The KS ground is supplied by the control module through a low reference circuit. The control module learns a minimum noise level, or background noise, at idle from the KS and uses calibrated values for the rest of the RPM range.

In order to determine which cylinders are knocking, the control module only uses KS signal information when each cylinder is near Top Dead Center (TDC) of the firing stroke. If knock is present, the signal will range outside of the noise channel. If the control module has determined that knock is present, it will retard the ignition timing to attempt to eliminate the knock. The control module will always try to work back to a zero compensation level, or no spark retard.

Component Description

The Knock Sensor (KS) is a piezo-electric (pressure-sensitive) electronic device that enables the Powertrain Control Module (PSM) to control the ignition timing for optimum performance, and to protect the engine from potentially damaging levels of detonation. The PCM uses the KS system to test for abnormal engine noise that may indicate detonation, which is also known as spark knock.

Removal & Installation



Specific to:

Chevrolet Silverado 1500 2008

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Raise and support the vehicle safely.
  6.  
  7. Remove the skid plates for access, if equipped.

    Click image to see an enlarged view

    Fig. Skid plate and related components-type one



    Click image to see an enlarged view

    Fig. Skid plate and related components-type two

  8.  
  9. If necessary, remove the tire and wheel assembly.
  10.  
  11. If equipped, remove the knock sensor shield.
  12.  
  13. Unplug the harness connection from the knock sensor.
  14.  
  15. Remove the bolt securing the sensor, then remove it from the engine.

    Click image to see an enlarged view

    Fig. Knock sensor mounting-4.3L engines



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    Fig. Knock sensor mounting-4.8L, 5.3L & 6.0L engines

  16.  

To install:


NOTE
Be sure to use new fasteners, as required.

  1. Position the sensor on its mounting.
  2.  
  3. Tighten the bolt to 18 ft. lbs. (25 Nm).
  4.  
  5. Continue the installation in the reverse order of the removal procedure.
  6.  

Testing



Specific to:

Chevrolet Silverado 1500 2008


NOTE
Refer to the Electrical Wiring Diagram for component and connector locations, connector views, and circuit-specific information.

Knock Sensor (KS) Strategy

Specific to:

Chevrolet Silverado 1500 2008

The Knock Sensor (KS) system uses one or two broadband one-wire sensors. The Knock Sensor generates an AC voltage signal of varying amplitude and frequency based on the engine vibration. The amplitude and frequency are dependent upon the level of knock that the KS detects. The control module receives the KS signal through a signal circuit, and the KS ground is supplied by the engine block through the sensor housing.

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Fig. Active Knock Sensor (KS) Pattern

Related Diagnostic Trouble Codes

Specific to:

Chevrolet Silverado 1500 2008



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Fig. Related Diagnostic Trouble Codes

 
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