GM Corvette 1984-1996 Repair Guide

Knock Sensor (KS)

Print

OPERATION



See Figure 1

Some vehicles use two knock sensors.

The knock sensor is usually mounted to the right and/or left 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: View of a 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 Figures 2, 3 and 4

  1. Disconnect the negative battery cable.
  2.  
  3. Raise and properly support the vehicle.
  4.  
  5. Position a suitable drain pan under the vehicle, then drain the engine coolant.
  6.  
  7. If equipped, remove the knock sensor shield.
  8.  
  9. Disconnect the knock sensor wiring harness.
  10.  



Click image to see an enlarged view

Fig. Fig. 2: Location of the left knock sensor on VIN P engines



Click image to see an enlarged view

Fig. Fig. 3: The VIN P engine also has a right side knock sensor



Click image to see an enlarged view

Fig. Fig. 4: Location of the knock sensor on VIN J engines

  1. Remove the knock sensor from the engine block.
  2.  


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

  1. Installation is the reverse of removal. Prior to installing the sensor, Do NOT apply any thread sealer to the KS threads. The sensor is coated at the factory and any additional sealant you may apply will negatively affect the ability of the sensor to detect knocking or pinging. Tighten the sensor to 14 ft. lbs. (19Nm).
  2.  

 
label.common.footer.alt.autozoneLogo