Products suited to this guided test*
  • BNC to BNC Cable with Earth Clamp

  • Coil On Plug (COP) and Signal Probe

  • *At Pico we are always looking to improve our products. The tools used in this guided test may have been superseded and the products above are our latest versions used to diagnose the fault documented in this case study.

Ignition - coil-on-plug secondary COP probe

The purpose of this test is to check secondary ignition event from an individual COP unit using the COP probe.

How to perform the test

View connection guidance notes.

  1. Connect the COP signal probe to PicoScope channel A. Ensure the probe lead has a good earth connection on the engine.
  2. Start the engine and allow it to idle.
  3. Minimize the help page. You will see that PicoScope has displayed an example waveform and is preset to capture your waveform.
  4. Start the scope to see live data.
  5. Place the flat surface of the probe squarely on top of the suspect coil, adjust the probe position until a clear waveform is seen.
  6. With your live waveform on screen stop the scope.
  7. Stop the engine and ensure the ignition remains off.
  8. Use the Waveform Buffer, Zoom and Measurements tools to examine your waveform.

Example waveform

Waveform notes

The example waveform show a typical ignition picture from an engine fitted with electronic ignition. The waveform has been taken from the coil-on-plug.

Waveform Library

Go to the drop-down menu bar at the lower left corner of the Waveform Library window and select, COP (Coil on plug ignition) secondary voltage

Further guidance

The operation of the coil-on-plug is essentially the same as any other ignition system. Each coil has a low primary resistance, and steps up the primary system voltage to as much as 40,000 volts to produce a spark at the plug.

The only real difference between COP and other ignition systems is that each COP coil is mounted directly onto the spark plug, so the voltage goes directly to the plug electrodes without having to pass through a distributor or plug leads. This direct connection method delivers the strongest spark possible and improves the reliability of the ignition system.

Using individual coils for each spark plug also means the coils have more time between each firing. Increasing the 'coil saturation' time (the time the voltage to the coil is on to build up its magnetic field) increases the coil output voltage at high rpm when misfire is most likely to occur.


This help topic is subject to changes without notification. The information within is carefully checked and considered to be correct. This information is an example of our investigations and findings and is not a definitive procedure. Pico Technology accepts no responsibility for inaccuracies. Each vehicle may be different and require unique test settings.

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Guided test: COP testing using mV range for Secondary Ignition