ES300 1992-1997

Knock Sensor

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Location



Specific to:

Lexus ES300 1994-1999



Click image to see an enlarged view

Fig. Knock Sensor (KS)-1999 models shown, other models similar

Operation



Specific to:

Lexus ES250 1990-1991

Lexus ES300 1992-1999

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:

Lexus ES300 1994-1996

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air intake chamber assembly.
  4.  
  5. Disconnect the injector connectors.
  6.  
  7. Disconnect the heater hose from the intake manifold.
  8.  
  9. Remove the 9 bolts, 2 nuts, 2 plate washers and intake manifold assembly.
  10.  
  11. Remove the right-hand engine mounting stay and water outlet:
    1. Disconnect the following hoses and connectors:

      Radiator inlet hose
       
      Engine coolant reservoir hose
       
      ECT sensor connector
       
      ECT switch connector
       
      Ground strap connector
       

    2.  
    3. Remove the 3 bolts and right-hand mounting stay.
    4.  
    5. Remove the wire band.
    6.  
    7. Disconnect the water bypass hose from the inlet housing.
    8.  
    9. Remove the 2 bolts, 2 nuts, 2 plate washers and water outlet.
    10.  
    11. Remove the 2 gaskets.
    12.  

  12.  
  13. Disconnect the knock sensor connector.
  14.  
  15. Remove the knock sensor.

    Click image to see an enlarged view

    Fig. Remove the knock sensor

  16.  

To install:

  1. Install the knock sensor. Tighten to 29 ft. lbs. (39 Nm).
  2.  
  3. Connect the knock sensor connector.
  4.  
  5. Install the right-hand engine mounting stay and water outlet:
    1. Install 2 new gaskets on the cylinder head.
    2.  
    3. Install the water outlet with the 2 bolts, 2 plate washers and 2 nuts. Tighten to 11 ft. lbs. (15 Nm).
      NOTE
      Do not scratch the seal surface of the water outlet with the stud bolt.

    4.  
    5. Connect the water bypass hose to the inlet housing.
    6.  
    7. Install the wire band.
    8.  
    9. Install the right-hand mounting stay and tighten the 3 bolts to 23 ft. lbs. (31 Nm).
    10.  

  6.  
  7. Install the intake manifold assembly with the 9 bolts, 2 plate washers and 2 nuts. Tighten to 11 ft. lbs. (15 Nm).
  8.  
  9. Connect the heater hose to the intake manifold.
  10.  
  11. Connect the injector connectors.
  12.  
  13. Tighten the water outlet mounting bolts and nuts to Tighten to 11 ft. lbs. (15 Nm).
  14.  
  15. Install the air intake chamber assembly.
  16.  

Specific to:

Lexus ES300 1997-1999

  1. Disconnect the negative battery cable.
  2.  
  3. For 1999 models, remove the V-Bank cover.
  4.  
  5. Remove the air cleaner hose/resonator.
  6.  
  7. Remove the right-hand engine mounting stay.
  8.  
  9. Remove the intake manifold assembly and water outlet.
  10.  
  11. Disconnect the knock sensor connector.
  12.  
  13. Using SST (SST 09817-16011), remove the knock sensor.

    Click image to see an enlarged view

    Fig. Remove the knock sensor

  14.  

To install:

  1. Install the knock sensor. Tighten to 29 ft. lbs. (39 Nm).
  2.  
  3. Connect the knock sensor connector.
  4.  
  5. Install the intake manifold assembly and water outlet.
  6.  
  7. Install the right-hand engine mounting stay.
  8.  
  9. Install the air cleaner hose.
  10.  

Testing



Specific to:

Lexus ES250 1990-1991

Lexus ES300 1992-1999


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

Knock Sensor Strategy

Specific to:

Lexus ES250 1990-1991

Lexus ES300 1992-1999

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.

Click image to see an enlarged view

Fig. Active Knock Sensor (KS) Pattern

Related Diagnostic Trouble Codes

Specific to:

Lexus ES250 1990-1991

Lexus ES300 1992-1999



Click image to see an enlarged view

Fig. Related Diagnostic Trouble Codes

 
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