Troubleshooting

DTC P0325 Knock Sensor Circuit Malfunction (Knock Sensor 1)

CIRCUIT DESCRIPTION
Knock sensors are fitted one each to the front and rear of the left side 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

Step 1:

Step 2:

Step 3:

Step 4:

INSPECTION PROCEDURE

HINT: DTC P0325 is for the knock sensor circuit on the front side.
DTC P0330 is for the knock sensor circuit on the rear side.

Reference INSPECTION USING OSCILLOSCOPE
- With the engine racing (4,000 rpm) measure waveform 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 123 m sec. (Normal mode vibration frequency of knock sensor: 8.1 KHz).





HINT: If normal mode vibration frequency is not 8.1 KHz, the sensor is malfunctioning.