G6 2005-2007

Knock Sensor

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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.

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 amplitude and frequency are dependant upon the level of knock that the KS detects. The control module receives the KS signal through the signal 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. 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



2.4L Engine
  1. Disconnect the Knock Sensor (KS) electrical connector.
  2.  
  3. Remove the KS electrical connector clip from the oil level indicator tube bracket.
  4.  
  5. Remove the oil level indicator tube.
  6.  
  7. Remove the KS bolt.
  8.  
  9. Remove the KS.
  10.  

To Install:


NOTE
Rotate the pigtail 90 degrees from vertical before securing the fastener.

  1. Install the KS.
  2.  
  3. Install the KS bolt and tighten to 18 ft. lbs. (25 Nm).
  4.  
  5. Connect the KS electrical connector.
  6.  
  7. Install the oil level indicator tube.
  8.  
  9. Install the KS electrical connector clip to the oil level indicator tube bracket.
  10.  

3.5L Engine
  1. Raise and support the vehicle.
  2.  
  3. Disconnect the engine wiring harness electrical connector from the Knock Sensor (KS).
  4.  
  5. Remove the knock sensor bolt and sensor.
  6.  

To Install:

  1. Position the knock sensor to the engine block and install the knock sensor bolt. Tighten the bolt to 18 ft. lbs. (25 Nm).
  2.  
  3. Connect the engine wiring harness electrical connector to the knock sensor.
  4.  
  5. Lower the vehicle
  6.  

3.6L Engine
  1. Remove the exhaust manifold lower heat shield. Bank 1 knock sensor only.
  2.  
  3. Disconnect the engine wiring harness electrical connector from the knock sensor.
  4.  
  5. Loosen the knock sensor bolt and remove the knock sensor.
  6.  

To Install:

  1. Position the knock sensor and tighten the knock sensor bolt to 17 ft. (23 Nm).
  2.  
  3. Connect the engine wiring harness electrical connector to the bank 1 knock sensor.
  4.  
  5. Install the exhaust manifold lower heat shield. Bank 1 knock sensor only.
  6.  

3.9L Engine
  1. Raise and support the vehicle.
  2.  
  3. Disconnect the knock sensor electrical connector.
  4.  
  5. Loosen and remove the knock sensor.
  6.  

To Install:

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

Testing





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Fig. Knock sensor electrical connector 2.4L engine



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Fig. Knock sensor 1 and 2 electrical connector 3.5L-3.9L engines



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Fig. Knock sensor 1 and 2 electrical connector 3.6L engine

  1. Connect the Digital Multimeter (DMM) from the Knock Sensor (KS) signal circuit terminal A to the KS signal circuit terminal B on the sensor side of the KS harness connector.
  2.  
  3. Set the DMM to the 400 mV AC hertz scale and wait for the DMM 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 the DMM does not display a fluctuating frequency suspect faulty knock sensor.
  10.  

 
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