Knock Sensor: Testing and Inspection

KNOCK SENSOR (KS)
The knock sensor is attached to the cylinder block and senses engine knocking conditions.
A knocking vibration from the cylinder block is applied as pressure to the piezoelectric element. This vibrational pressure is then convened into a voltage signal which is delivered as output. If engine knocking occurs, ignition timing is retarded to suppress it.




CIRCUIT DIAGRAM







HARNESS INSPECTION PROCEDURE




SENSOR INSPECTION
1. Disconnect the knock sensor connector.
2. Measure resistance between the terminal 2 and 3.

Standard value about 5 m Ohm @ 20°C (68°F)

3. If the resistance is continual, replace the knock sensor.

Tightening torque: 16-28 Nm (11.8-18.4 ft.lbs.)

4. Measure the capacitance between the terminal 2 & 3.

Standard value 800-1600 pF




TROUBLESHOOTING PROCEDURES

TROUBLESHOOTING HINTS
When knock sensor signal is abnormally low.