Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

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Oscilloscope Patterns and Waveforms

INSPECTION USING OSCILLOSCOPE



- With the engine racing (4,000 rpm) measure 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 151 microseconds (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.