Reading Waveforms
Compare the shape, amplitude, frequency and noise of a signal against a known-good reference.
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What you will learn
- Assess a waveform systematically
- Recognise weak, missing and noisy signals
- Decide what the shape tells you
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A waveform is a picture of what the sensor or actuator is doing. A crank sensor sine wave that is distorted, a coil event with the wrong shape, or an injector pulse that does not return to supply all point to specific faults the scanner alone cannot reveal.
Read a waveform in a fixed order: is it present, what is the amplitude, what is the frequency, is the shape clean, and is there noise? Then compare it with a known-good signal for the same engine.
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Key points
- Presence, amplitude, frequency, shape, noise — in that order.
- A known-good reference makes judgement fast.
- Record while reproducing intermittent faults.
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Key points
- Shape reveals the physical event
- Amplitude and frequency tell the story
- Capture intermittent faults while reproducing them
All values shown are training examples. Real thresholds depend on the manufacturer, engine, temperature and system — always confirm with the vehicle service documentation.
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