Montana, Silhouette, Venture 2000-2005

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 Engine
  1. Raise and safely support the vehicle.
  2.  
  3. Disconnect the knock sensor wiring harness electrical connector.
  4.  
  5. Remove the knock sensor.
  6.  

To install:


CAUTION
DO NOT apply thread sealant to the sensor threads. The sensor threads are coated at the factory. Applying additional sealant affects the sensors ability to detect detonation.

  1. Install the knock sensor and tighten to 18 ft. lbs. (25 Nm).
  2.  
  3. Connect the knock sensor wiring harness.
  4.  
  5. Lower the vehicle.
  6.  

3.9L Engine
  1. Raise and safely support the vehicle.
  2.  
  3. Remove the radiator air baffle, if removing the knock sensor from Bank 1.
  4.  
  5. Remove the right front wheel and engine splash shield, if removing the knock sensor from Bank 2.
  6.  
  7. Disconnect the wiring harness from the knock sensor.
  8.  
  9. Loosen and remove the knock sensor.
  10.  

To install:


CAUTION
DO NOT apply thread sealant to the sensor threads. The sensor threads are coated at the factory. Applying additional sealant affects the sensors ability to detect detonation.

  1. Install the knock sensor and tighten to 18 ft. lbs. (25 Nm).
  2.  
  3. The remainder of the installation is the reverse order of removal.
  4.  

 
label.common.footer.alt.autozoneLogo