GM Corsica/Beretta 1988-1996 Repair Guide

Knock Sensor (KS)

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OPERATION



See Figure 1

The knock sensor is usually mounted to the right lower side of the engine block. When spark knock or pinging is present, the sensor produces a voltage signal which is sent to the PCM. The PCM will then retard the ignition timing based on these signals.



Click image to see an enlarged view

Fig. Fig. 1: Typical Knock Sensor (KS)

TESTING



  1. Connect a timing light to the vehicle, then start the engine.
  2.  
  3. Check that the timing is correct before testing the knock sensor operation.
  4.  
  5. If the timing is correct, tap on the front of the engine block with a metal object while observing the timing to see if the timing retards.
  6.  
  7. If the timing does not retard, the knock sensor may be defective.
  8.  

REMOVAL & INSTALLATION



See Figure 2

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


CAUTION
The knock sensor is mounted in the engine block cooling passage. Engine coolant in the block will drain when the sensor is removed.



Click image to see an enlarged view

Fig. Fig. 2: Knock sensor mounting - 3.1L (VIN M) engine shown, other engines similar

  1. Installation is the reverse of removal. Tighten the sensor to 14 ft. lbs. (19 Nm).
  2.  

 
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