How to Test a CDI Box With a Multimeter?

How to Test a CDI Box With a Multimeter?

There are many different electrical components in a motorcycle, and if one of them isn’t working properly, it can cause big problems. One of the most important electrical components is the CDI box.

If your motorcycle isn’t starting or is running poorly, it may be due to a faulty CDI box. Fortunately, you can test the CDI box with a multimeter to see if it’s working properly.

What is a CDI Box?

A CDI box, or capacitive discharge ignition box, is an electronic component found on some motorcycles. It’s responsible for providing power to the ignition system and triggering the sparks that ignite the fuel mixture in the engine [1].

It is very important because it helps to produce a more powerful spark which can result in better performance and fuel economy. Moreover, it is also necessary for the reliable starting of the engine.

CDI boxes can fail, leading to a loss of power or even complete engine failure. If you’re experiencing any problems with your motorcycle’s ignition system, it’s important to test the CDI box for defects.

What is a CDI Box?

So, If your motorcycle isn’t running well, or if you’re just doing some routine maintenance, it’s a good idea to test the CDI box to make sure it’s functioning properly. This can be easily done with a multimeter.

How do CDI Boxes work?

CDI Boxes work by using a step-up transformer to increase the voltage from the battery. This increased voltage is then sent to the ignition coil, which creates a spark that ignites the fuel in the engine. The CDI Box also regulates the timing of this spark, ensuring that it happens at just the right moment.

In addition to regulating the spark, the CDI Box also monitors the engine’s speed and adjusts the timing of the spark accordingly. This helps to keep the engine running smoothly regardless of its speed.

The principle behind the CDI Box is simple, but the actual construction can be quite complex. If you are not sure how to test a CDI Box, it is best to leave the job to a professional.

What is a Multimeter?

A multimeter is an electronic device that can measure voltage, current, and resistance. It has a variety of probes that can be inserted into different ports to make these measurements. Multimeters are used to test the functionality of electrical components in cars and other devices [2].

Multimeters come in a variety of shapes and sizes, but all of them have three basic parts: the meter itself, the probes, and the dial.

  • The meter is the rectangular part of the multimeter that displays the measurements.
  • The probes are the long, thin pieces that attach to the meter and are used to make contact with electrical components.
  • The dial is the knob on the front of the multimeter that sets the measurement range.

What is a Multimeter?

Multimeters can be used to test a wide variety of electrical components, including:

  • batteries
  • diodes
  • fuses
  • relays
  • switches
  • CDI boxes

There are both digital and analog multimeters. Digital multimeters display the measurements in numbers, while analog multimeters use a needle to indicate the measurement.

Some devices offer additional features beyond basic measurements, such as the ability to test capacitors or frequency.

In addition to testing electrical components, multimeters can also be used for basic troubleshooting. If a device isn’t working, a multimeter can help identify the problem.

Pros and Cons of using Multimeter for testing CDI box

There are both advantages and disadvantages.


  • Multimeters are relatively inexpensive  and easy to use
  • They can help you troubleshoot electrical problems
  • They are easy to use and can be used by anyone
  • They provide a great deal of information about the electrical system being tested


  • Multimeters can be inaccurate if not used correctly
  • They can be damaged if used improperly
  • They require some knowledge of electrical systems in order to use them effectively.

Overall, multimeters are a great tool for testing CDI boxes and other electrical systems. However, they must be used properly in order to be effective.

Pros and Cons of using Multimeter for testing CDI box

If you are unsure how to use a multimeter, consult an experienced technician before attempting to test a CDI box with one. By using a multimeter correctly, you can help ensure that your CDI box is in good working order and that your motorcycle is safe to ride.

Step by Step Guide to Testing your CDI Box

Testing a CDI box with a multimeter is a simple process that can be completed in just a few steps. By following these steps, you will be able to test the functionality of your CDI box and determine if it is working properly.

To test a CDI box with a multimeter, you will need:

  • A multimeter
  • A CDI box

Grab all you need and let’s get started!

  1. The first step is to remove the cover of the CDI box. This can be done by unscrewing the screws that hold it in place. Once the cover is removed, you should be able to see the electronic components inside.
  2. Next, you will need to attach one end of the wire to the positive terminal of the multimeter and the other end to the negative terminal. Be sure to attach the wires securely so that there is no chance of them coming loose during testing.
  3. Once the wires are in place, you can turn on the multimeter by turning the knob on the side. The needle should move to the right and stay in the green area.
  4. Now, you can test the CDI box by touching the probes to the terminals on the box. The needle on the multimeter should move when you touch the probes together. If it does not move, there may be a problem with your CDI box.
  5. If everything is working properly, your multimeter should show a reading of between 0 and 50. If the reading is outside of this range, there may be a problem with your CDI box.
  6. If you are having trouble getting a reading from your multimeter, try touching the probes to different parts of the terminals on the CDI box. Be sure to test both the positive and negative terminals.
  7. Once you have tested the CDI box, it is important to reattach the cover to the box. This will protect the electronic components from damage and keep them from getting wet.

Be sure to test your CDI box regularly to ensure that it is working properly. If you notice any problems with your bike, such as a loss of power or poor performance, it may be caused by a faulty CDI box.

By following these steps, you can test your CDI box quickly and easily.

Common Symptoms of a Bad CDI Box

When a CDI box is bad, the motorcycle may experience any of the following symptoms:

  • The engine will not start.
  • The engine will start but will not stay running.
  • The bike will backfire.
  • There will be decreased performance or power.
  • The bike will hesitate when accelerating.
  • The bike will not reach top speed.

If you are experiencing any of these symptoms, it is likely that your CDI box needs to be replaced.

Common Symptoms of a Bad CDI Box

However, before replacing you should test your CDI box with a multimeter to make sure that is the problem.

Safety Precautions

When testing a CDI box with a multimeter, always take precautions to ensure your safety. Make sure the bike is in neutral and that the ignition is off before beginning any tests. Failure to do so could result in serious injury.

Never touch any of the electrical contacts while the bike is running. You could be seriously injured if you come into contact with even a small amount of current.

In addition, be sure to use the correct test leads when testing a CDI box. Improper use of test leads can result in damage to the meter or the CDI box.

Don’t forget to disconnect the battery before starting any tests. This will help prevent accidental shorts and keep the electrical current flowing through the system to a minimum.

Always wear safety glasses when working with electrical components. This will help protect your eyes from any potential injuries.

If you’re not comfortable testing the CDI box yourself, take it to a qualified mechanic. They will be able to test it and fix any problems that may be causing your bike to stall or hesitate.

Comparison of CDI Box Testing Indicators with a Multimeter

This table compares various indicators to determine if the CDI box is functioning properly.

Indicator Test Method Expected Reading Interpretation
Primary Coil Resistance Ohmmeter 0.2 to 0.5 ohms Reading higher than expected indicates a problem with the primary coil
Secondary Coil Resistance Ohmmeter 5 to 10 kilo-ohms Reading outside this range indicates a problem with the secondary coil
Peak Voltage Output Voltmeter 100 volts or more Low reading indicates a weak spark and potential CDI box issue
Charge Time Stopwatch Within manufacturer’s specifications Longer than expected charge time can indicate a problem with the CDI box or the charging system

To test the CDI box with a multimeter, several indicators need to be checked. The primary coil resistance should be between 0.2 to 0.5 ohms. If the reading is higher than expected, it indicates a problem with the primary coil. The secondary coil resistance should be between 5 to 10 kilo-ohms. Any reading outside this range indicates a problem with the secondary coil. The peak voltage output should be 100 volts or more, and a low reading indicates a weak spark and potential CDI box issue. Finally, the charge time should be within the manufacturer’s specifications. A longer than expected charge time can indicate a problem with the CDI box or the charging system.

Read more guides about multimeters:


Do you need a CDI ignition battery?

A CDI ignition battery is not necessary to test a CDI box. However, it may be helpful to have one handy in order to better understand the results of your tests.

Can a CDI box cause a weak spark?

A CDI box can cause a weak spark. By testing your CDI box with a multimeter, you can determine whether or not it is causing this issue.

Are CDI boxes universal?

CDI boxes are not universally compatible. Each box is made to work with a specific make and model of motorcycle.

How often should I test my CDI box?

There is no set frequency for testing a CDI box. However, it is generally recommended that you check your box at least once a year to ensure its proper functioning.

Can a CDI box cause my bike to not start?

A CDI box can cause your bike to not start if it is not properly functioning.

What should I do if my CDI box is bad?

If your CDI box is bad, you will need to replace it. Be sure to check your bike’s owner’s manual to ensure that you are using the correct CDI box.

If you have any other questions about testing a CDI box, please don’t hesitate to ask us in the comments section below. We’re happy to help!

Useful Video: Testing motorcycle CDI unit with multimeter

Final Thoughts

Multimeter usage is a critical skill that every car mechanic should know. In this article, we have shown you how to use a multimeter to test a CDI box. Always remember to be safe when working with electrical equipment, and if you are unsure about anything, consult with a professional.

In addition, always test components before installing them in your car. This will help you avoid costly mistakes and keep your car running smoothly.

Testing a CDI box with a multimeter is a fairly simple process. By following the steps outlined in this article, you should be able to test your CDI box quickly and easily.

I hope you found this article helpful and informative. If so, please consider sharing it with your friends and family.

If you have any hints or tips, please feel free to share them in the comment section below.

Thanks for reading! Be sure to check out our other blog posts for more information about automotive repair and maintenance.