DIS primary ignition voltage (dual driver) and current

The purpose of this test is to monitor the driver voltages and the current draw during both driver events, making it possible to see whether both coils draw the same amount of current during the operation cycle.

Connection guidance

Connection for diagnostic work will vary dependent on application.

Technicians should whenever possible gain access to the test circuit without damage to seals and insulation. If this is not possible then make sure appropriate repairs are completed.

General connection advice

PicoScope offers a range of options within the test kits.

Dependent on difficulty of access, choose from:

1. Breakout leads.
2. Back-pinning probes.

Testing sensors and actuators (to include relevant circuit/connectors):

• When testing a sensor, it is desirable to gain access at the control module.
• When testing an actuator, it is desirable to gain access at the actuator.

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

Note;

A 10:1 attenuator is used on both channel A and Channel B.

1. Use manufacturer data to identify circuit functions.
2. Connect a 10:1 attenuator into channel A of your PicoScope. Then connect channel A to one of the coil driver circuits.
3. Connect a 10:1 attenuator into channel B of your PicoScope. Then connect channel B into the second coil driver circuit.
4. Connect the low amp current clamp to PicoScope channel C. Select the 20 A scale, switch on and zero the scope before connecting around the coil unit power supply circuit.
5. Start the engine and run at idle.
6. Minimise the help page and with the example waveform on your screen PicoScope has already selected suitable scales for you to capture a waveform.
7. Start the scope to see live data.
8. With your live waveforms on screen stop the scope.
9. Turn off the engine.
10. Use the Waveform Buffer and Zoom tools to examine your waveform.

Example waveform

Waveform notes

The waveform shows the driver voltages for both windings in the ignition coil. It also shows the current drawn during both driver events, allowing you to see if both coils are drawing the same amount of current during the operating cycle.

Waveform Library

Go to the drop-down menu bar at the lower left corner of the Waveform Library window and select, DIS / wasted spark ignition primary voltage

Further guidance

Distributorless Ignition System (DIS)

DIS has major advantages over the distributor-based ignition system. These advantages include an absence of rotating high-voltage distribution components, and far lower levels of electromagnetic interference.

DIS is fitted only to vehicles that have an even number of cylinders, such as 2, 4, 6 or 8. This is because two cylinders are connected to one coil, which can send a spark to both cylinders at the same time. This system is commonly known as a wasted spark system. The two spark plugs are arranged so that one is fired on the power stroke of the engine and the other on the exhaust stroke of the opposing cylinder, offset by 360 degrees. After a complete rotation of the engine the two cylinders are now on the opposing strokes and the two spark plugs fire again but with opposite roles.

On a four-cylinder engine, there are two coils with individual drivers that tend to operate cylinders 1 and 4, and 2 and 3. This means there is a dual spark every 180 degrees, with one of those sparks wasted on an exhaust stroke of the opposing cylinder which is firing on the power stroke.

For further information, see the following topics:

• Primary ignition voltage
• Primary ignition current

GT395-1

Suitable accessories