Oscilloscope Patterns and Waveforms

With the engine racing (4,000 rpm) measure waveform between terminal KNK of engine control module and body ground. The correct waveform is as shown.:

Spread the time on the horizontal axis, and confirm that the period of the wave is 123 microseconds (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.