DIS ignition: secondary vs primary voltage and current

The purpose of this test is to monitor the primary current and voltage vs the secondary voltage of a DIS unit.

Connection guidance

Note: This helpfile refers to a 10:1 attenuator. If you are using a 20:1 attenuator please adjust the Probe settings for the relevant channel. These settings can be found under the Channel Options button, then: Probe > 20:1 Attenuator.

How to perform the test



Uninsulated HT pickups are designed to clip around double-insulated HT cables only – they are not designed for direct connection to a hazardous live voltage. To prevent injury or death, switch off the engine and secure against restart. Clean and inspect the HT lead for damage to insulation and fit only to undamaged fully insulated leads. Ensure that leads are safely clear of hot and / or rotating parts. The engine can now be restarted for the test duration.

Channel A: Primary voltage

  1. Disconnect the primary wiring to the DIS coil and reconnect it using a 6-way Universal Breakout Lead as shown in Figure 1.
  2. Plug the 10:1 Attenuator into Channel A on the PicoScope.
  3. Plug a BNC to 4-mm test lead into the attenuator.
  4. Fit a large black clip onto the black test plug (earth) and clip it on the battery negative terminal.
  5. Fit the coloured plug on the BNC test lead to the socket on the 6-way Breakout Lead that carries the coil's negative (or number 1) terminal.

Channel B: Secondary voltage

  1. Plug a Secondary ignition pick-up lead into Channel B on the PicoScope.
  2. Place the lead's clip onto a suitable earth.
  3. Fit the HT clip onto one of the engine's negatively-fired plug leads as shown in Figure 1.

If the live waveform is not shown or is upside-down, a positively-fired plug has been selected by mistake. Either choose a different plug lead to test or load the example secondary positive waveform from the drop-down menu.

Channel C: Primary current

  1. Connect the low-amp current clamp to Channel C of the PicoScope.
  2. Select the 20 A range and switch the current clamp on.
  3. Press the zero button before connecting the clamp to the circuit.
  4. Place the current clamp around the primary feed wire on the 6-way Universal Breakout Cable as illustrated in Figure 1.

Example waveform

Further guidance

For further information, see the following topics:

  • Primary voltage
  • DIS secondary voltage
  • Primary current


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.

Suitable accessories

  • Secondary ignition pickup (capacitive with BNC)


  • Premium 6-way breakout lead set


  • Back-pinning Probe Set


  • Flexible Back-pinning Probe


  • Large Dolphin/Gator Clips


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Guided test: Secondary vs Primary Voltage and Current