Circuit Description
A flat type knock sensor (non-resonant type) has the structure that can detect vibration in a wider band of the frequency from about 6 kHz to 15 kHz and has the following features.
Knock sensors are fitted on the cylinder block to detect engine knocking.
The knock sensor contains a piezoelectric element which generates voltage when it becomes deformed.
The generation of the voltage occurs when the cylinder block vibrates due to the knocking. If the engine knocking occurs, in order to suppress it, the ignition timing is retarded.
HINT:
If the ECM detects the DTC P0325,P0327 and P0328, it enters fail-safe mode in which the corrective retarded angle value is set to its maximum value.
Reference: Inspection by using an oscilloscope.
- After warming up, run the engine at 2,500 RPM, check the waveform between terminals KNK1 and EKNK of the ECM connector.