Troubleshooting
P0325 - Knock Sensor 1 Circuit MalfunctionCIRCUIT DESCRIPTION
DTC Detecting Condition:
The knock sensor is fitted to 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.
HINT: If the ECM detects 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 - 3:
Step 4:
INSPECTION PROCEDURE
HINT: Read freeze frame data using TOYOTA hand-held tester or OBD II scan tool. Because freeze frame records the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining whether the vehicle was running or stopped, the engine warmed up or not, the air-fuel ratio lean or rich, etc. at the time of the malfunction.
Reference: INSPECTION USING OSCILLOSCOPE
- With the engine racing (4,000 rpm) measure between terminal KNK of the ECM connector and body ground.
HINT: The correct waveforms are as shown.
- Spread the time on the horizontal axis, and confirm that period of the wave is 80 sec.
(Normal mode vibration frequency of knock sensor: 12.5 kHz (1ZZ-FE), 8.0 kHz (2ZZ-GE))
HINT: If normal mode vibration frequency is not 7.6 kHz the sensor is malfunctioning.