Troubleshooting

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.





DETECTING CONDITION
If the 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

INSPECTION PROCEDURE










HINT:
- DTC P0325 is for right bank knock sensor circuit.
- DTC P033O is for left bank knock sensor circuit.

Reference

INSPECTION USING OSCILLOSCOPE





- With the engine racing (4,000 rpm) measure between terminals KNK1, KNK2 of ECM and body ground.

HINT: The correct waveform appears as shown in the illustration.





- Spread the time on the horizontal axis, and confirm that period of the wave is 151 micro secs. (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.