P0325

CIRCUIT DESCRIPTION
Knock sensors are fitted one each to the right bank and left bank of the cylinder block to detect engine knocking. This sensor contains a piezoelectric element which generates a voltage when it becomes deformed, which occurs when the cylinder block vibrates due to knocking. If engine knocking occurs, ignition timing is retarded to suppress it.





If the Engine Control Module (ECM) detects the above diagnosis conditions, it operates the fail safe function in which the corrective retard angle value is set to the maximum value.

WIRING DIAGRAM

Knock Sensors Circuit:

INSPECTION PROCEDURE
HINT: DTC PO325 is for the right bank knock sensor circuit. DTC PO33O is for the left bank knock sensor circuit.











INSPECTION USING OSCILLOSCOPE



- With the engine racing (4,000 rpm) measure between terminals KNK1, KNK2 of ECM and body ground.
HINT: The correct waveform is as shown.




- Spread the time on the horizontal axis, and confirm that period of the wave is 151 microseconds (Normal mode vibration frequency of knock sensor: 6.6 kHz).
HINT: If normal mode vibration frequency is not 6.6 kHz, the sensor is malfunctioning.