Knock Sensor: Testing and Inspection
KNOCK SENSOR
The knock sensor is attached to the side of the cylinder block to sense engine knocking. A knocking vibration from the cylinder block is applied as pressure to the piezoelectric element. This vibrational pressure is then converted into a voltage signal which is relayed to the ECM. If engine knocking occurs, ignition timing is retarded to suppress it.
Circuit Diagram:
HARNESS INSPECTION PROCEDURE
SENSOR INSPECTION
1. Disconnect the knock sensor connector and measure resistance between terminals 1 and 2.
Standard value: about 5 Mohm
2. If the resistance is continuous, replace the knock sensor.
Tightening torque
Knock sensor: 16 - 25 Nm (160 - 240 kg.cm, 11.8 - 18.4 lb.ft)
3. Measure the capacitance between terminals 1 and 2.
Standard value: 800 - 1600 pF