Canyon, Colorado 2006-2007

Knock Sensor

Print

Operation



The Knock Sensor (KS) system enables the control module to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The control module uses the KS system to test for abnormal engine noise that may indicate detonation, also known as spark knock.

This KS system uses one or two flat response two-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 amplitude and frequency are dependant upon the level of knock that the KS detects. 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. The control module uses the minimum noise level to calculate a noise channel. A normal KS signal will ride within the noise channel. As engine speed and load change, the noise channel upper and lower parameters will change to accommodate the normal KS signal, keeping the signal within the channel. 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. An abnormal KS signal will stay outside of the noise channel or will not be present. KS diagnostics are calibrated to detect faults with the KS circuitry inside the control module, the KS wiring, or the KS voltage output. Some diagnostics are also calibrated to detect constant noise from an outside influence such as a loose/damaged component or excessive engine mechanical noise.

Removal & Installation



3.5L And 3.7L Engines
Sensor 1
  1. Raise and support the vehicle.
  2.  
  3. Disconnect the engine wiring harness electrical connector from the KS (2).
  4.  
  5. Remove the KS retaining bolt.
  6.  
  7. Remove the KS (2) from the engine block.
    NOTE
    Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  8.  
  9. To install, reverse removal procedure. Tighten the knock sensor (KS) bolt to 18 ft. lbs. (25 Nm).
  10.  

Sensor 2


Click image to see an enlarged view

Fig. Removing knock sensor

  1. Raise and support the vehicle only high enough to access the knock sensor (KS) through the wheelhouse.
  2.  
  3. Remove the left wheelhouse liner.
  4.  
  5. Disconnect the engine wiring harness (2) electrical connector (3) from the KS (1).
  6.  
  7. Remove the KS retaining bolt. Remove the KS (1) from the engine block.
    NOTE
    Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  8.  
  9. To install, reverse removal procedure. Tighten the knock sensor (KS) bolt to 18 ft. lbs. (25 Nm).
  10.  

 
label.common.footer.alt.autozoneLogo