DIS primary ignition voltage and current (using the 10:1 attenuator)

The purpose of this test is to monitor the primary ignition voltage and current 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

Channel A: Primary Voltage

Plug the 10:1 Attenuator into Channel A on the PicoScope and plug a BNC test lead into the attenuator. Place a large black clip onto the black test plug (negative) and a back-pinning probe on the colored test lead (positive). Place the black clip onto the battery negative terminal and probe the coil's negative (or number 1) terminal with the back-pinning probe as illustrated in Figure 1.

Channel B: Primary Current

Connect the low-amp current clamp to Channel B of the PicoScope. Select the 20 A range if available and switch the current clamp on. Remember to zero  the clamp before connecting it to the circuit.

Place the current clamp directly onto the coil's supply cable and not around the loom that also contains the negative (or negatives depending on the ignition system). The connection is illustrated in Figure 1.

The example waveform shows a high voltage, so the scaling of the oscilloscope is adjusted to suit. It is important that the 10:1 Attenuator is used in all situations when a voltage exceeding 200 volts is being measured.

With the example waveform displayed on the screen you can now hit the space bar to start looking at live readings.

Example waveform

Further guidance

For further information, see the following topics:

  • Primary ignition voltage
  • Primary ignition 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

  • 20 A / 60 A DC (low amps) current clamp


  • Premium 6-way breakout lead set


  • Back-pinning Probe Set


  • Flexible Back-pinning Probe


  • Large Dolphin/Gator Clips


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Guided test: Primary Voltage (Single) vs Current