GM Lumina/Grand Prix/Cutlass Supreme/Regal 1988-1996

ESC Knock Sensor

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OPERATION



The Knock Sensor (KS) is mounted to the engine block. When spark knock, or pinging is present, then sensor produces a voltage signal which is sent to the ECM. The ECM will then retard the ignition timing based on these signals.

When a Knock Sensor problem is suspected, first perform a visual inspection. Most problems can be found in wiring harnesses and connectors.

TESTING



Perform a basic knock sensor test as follows. To perform this test, you will need a timing light.

  1. Connect a suitable timing light to the engine.
  2.  
  3. Start the engine and allow to warm up sufficiently.
  4.  
  5. Position the timing light near the timing marks on the harmonic balancer.
  6.  
  7. Locate the knock sensor.
  8.  
  9. Using a suitable metallic tool, tap on the intake manifold or side of the engine block; whichever is closer to the knock sensor. Do not strike hard or hit the sensor directly, light tapping should cause the knock sensor to react.
  10.  
  11. If the knock sensor is working, the ignition timing will begin to retard as you tap.
  12.  
  13. If the timing does not change, you will need to check voltage at the knock sensor harness connector. Also, make sure the connector is clean and making good connection.
  14.  

REMOVAL & INSTALLATION



  1. Disconnect the negative battery cable.
  2.  
  3. Raise and support the vehicle safely.
  4.  
  5. Detach the harness connector from the knock sensor.
  6.  
  7. Remove the sensor from the engine block.
  8.  

To install:

Do not apply thread sealant to sensor threads. Sensor is pre-coated at factory applying additional sealant will affect the sensors ability to detect detonation.

  1. Clean the threads on the engine block, where the sensor was installed. Install the sensor. Tighten to 11-16 ft. lbs. (15-22 Nm).
  2.  
  3. Attach the harness connector to the knock sensor.
  4.  
  5. Carefully lower the vehicle.
  6.  
  7. Connect the negative battery cable.
  8.  

 
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