GM Service Manual Online
For 1990-2009 cars only

Knock Sensor Replacement Bank 1

Removal Procedure

    Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

  1. Disconnect the ground cable from the battery.

  2. Object Number: 21520  Size: SH
  3. Disconnect the wiring harness from the knock sensor (1).

  4. Object Number: 21529  Size: SH
  5. Release the accessory drive belt by moving the belt tension roller in the direction of the arrow (clockwise).
  6. Remove the accessory drive belt from the belt tension roller.
  7. Remove the fastening bolts from the belt tension roller and remove the tension roller.
  8. Important: 

       • There is a bracket for a cable bundle on the lower fastening bolt.
       • The cable for the knock sensor is guided past the rear timing belt cover by several retaining clips. Only one retainer clip is shown.

  9. Remove the cable for the knock sensor from the retaining clips on the rear timing belt cover.
  10. Remove the lower air dam on the lower engine cover for access to the alternator.

  11. Object Number: 21521  Size: SH
  12. Remove the upper alternator fastening bolt (1). Loosen the lower alternator fastening bolt.
  13. Remove the air cooling duct from the alternator.
  14. Swing the alternator aside. Observe the cable routing for the knock sensor.
  15. Remove the knock sensor from the engine block.

Installation Procedure

  1. Thoroughly clean the mating surfaces of the knock sensor and the engine block. The entire contact surface of the knock sensor must lie directly on the engine block.

  2. Object Number: 21520  Size: SH

    Important: Do not use washers, spring washers, or toothed washers when installing the knock sensor. Tighten all of the fasteners to the proper torque.

  3. Install the knock sensor (1) into the engine block.
  4. Tighten
    Tighten the sensor to 22 N·m (16 lb ft).

    Important: The cable for the knock sensor is guided past the rear timing belt cover by several retaining clips. Only one retainer clip is shown.

  5. Install the cable for the knock sensor into the retaining clips. Ensure that the cable does not contact any moving parts.
  6. Connect the wiring harness for the knock sensor.
  7. Swing the alternator back into position. The cable for the knock sensor runs between the engine block and the alternator.
  8. Install the air cooling duct onto the alternator.

  9. Object Number: 21521  Size: SH
  10. Install/tighten the upper alternator fastening bolt (1) and the lower alternator fastening bolt (2).
  11. Install the belt tension roller to the cylinder head. The cable for the knock sensor runs between the cylinder head and the belt tension roller bracket.
  12. Install the belt tension roller fastening bolts. Install the bracket for the cable bundle at the lower fastening bolt.

  13. Object Number: 21529  Size: SH
  14. Rotate the belt tension roller in the direction of the arrow (clockwise).
  15. Important: Make sure that the accessory drive belt routing and running direction are correct.

  16. Install the accessory drive belt. Release the belt tension roller.
  17. The accessory drive belt tension is automatically adjusted by the tension roller.

  18. Install the air dam to the underside of the vehicle.

Knock Sensor Replacement Bank 2

Removal Procedure

  1. Remove the resonance chamber.
  2. Remove the cable from the retaining clips.

  3. Object Number: 21524  Size: SH
  4. Disconnect the wiring harness (1) from the knock sensor (2).
  5. Securely attach a scrap piece of wire about 36 inches long to the knock sensor pigtail. Later, this will be used as a pull wire to guide the new sensor pigtail back through the same routing.
  6. Loosen the three fastening bolts from the power steering pump pulley to the power steering pump.
  7. Mark the running direction of the accessory drive belt.

  8. Object Number: 21529  Size: SH
  9. Release the accessory drive belt by moving the belt tension roller in the direction of the arrow (clockwise), and remove the belt.
  10. Remove the power steering pump pulley.
  11. If present, remove the lower engine compartment cover, and the fastening bolts for the front left vibration damper from the front axle body bracket.

  12. Object Number: 21530  Size: SH
  13. Remove the lower nut (1) from the engine damping block.

  14. Object Number: 21539  Size: SH
  15. Loosen the four fastening bolts for the engine bracket (1) a few turns.

  16. Object Number: 21533  Size: SH

    Notice: Do not jack up the transmission by the pan. Use a suitable lifting point in order to prevent damage to the components.

  17. Using a hydraulic jack and a suitable adaptor, lift the transmission carefully until the pin comes out of the bracket.

  18. Object Number: 21539  Size: SH
  19. Remove all 4 fastening bolts (1) for the engine bracket.
  20. Remove the engine bracket with the engine damping block.
  21. Remove the knock sensor cable. Observe the cable routing. Gently pull the knock sensor pigtail through the wiring conduit and out. Stop when the pull wire is free of the conduit at both ends.
  22. Detach the knock sensor from the pull wire, leaving the pull wire in place.

Installation Procedure

  1. Thoroughly clean the mating surfaces of the knock sensor and the engine block. The entire contact surface of the knock sensor must lie directly on the engine block.

  2. Object Number: 21524  Size: SH

    Important: Do not use any washers, any spring washers, or any toothed washers when installing the Knock Sensor. Tighten all of the fasteners to the proper torque.

  3. Install the knock sensor (2) to the engine block.
  4. Tighten
    Tighten the sensor to 22 N·m (16 lb ft).

  5. Securely fasten the knock sensor pigtail to the pull wire that was left in place during the removal procedure.
  6. Use the pull wire in order to guide the knock sensor pigtail back through the proper route, out to the retaining clip at the power steering pump.
  7. Remove the pull wire.
  8. Important: When routing the cable for the knock sensor, ensure that the cable does not contact the exhaust manifold or any moving parts (e.g. accessory drive belt).

  9. Connect the wiring harness (1) to the knock sensor.
  10. Fasten the harness to the retaining clips.
  11. Install the pulley onto the power steering pump. Then, tighten the fastening bolts.

  12. Object Number: 21529  Size: SH
  13. Rotate the belt tension roller in the direction of the arrow (clockwise).
  14. Important: Make sure that the accessory drive belt routing and running direction are correct.

  15. Install the accessory drive belt. Release the belt tension roller.
  16. The accessory drive belt tension is automatically adjusted by the tension roller.

  17. Install the resonance chamber.
  18. Loosen the upper fastening nut for the engine damping block until the engine damping block can be moved in the engine bracket.

  19. Object Number: 21539  Size: SH
  20. Install the engine bracket (1) with the engine damping block. Install/tighten the 4 fastening bolts.
  21. Lower the transmission carefully until the guide pin and the fastening stud sit correctly in the front axle body bracket.

  22. Object Number: 21530  Size: SH
  23. Install/tighten the lower fastening nut (1) for the engine damping block.
  24. Install/tighten the fastening bolts for the front left vibration damper.
  25. Install the lower engine compartment cover, if so equipped.