How to Test Ignition Control Modules with a Multimeter (Guide)

Are you having trouble with ignition control module testing? If so, today we’re here to help. With this article, you will be able to learn to test the Ignition control module with a multimeter. The ignition control module test is not a difficult task at all.

In general to test ignition control modules with a multimeter, place the black probe of the multimeter on any vehicle part that is grounded. Now check each terminal using the red probe. Check the multimeter reading during the test. Similarly, don’t forget to crank up the engine while testing.

How to Identify That Your Ignition Control Module Needs Testing

The Ignition control module ICM plays a significant role in a vehicle’s ignition system. This ICM can cause some issues from time to time. So, identifying a bad ignition control module is crucial. But how can I do that? Here are some signs that indicate a bad ignition control system.

1. Check Engine Light

Whenever your vehicle suffers from a bad ICM, you can see the check engine light flashing on the dashboard. The check engine light is the most common indicator of a bad ICM.

2. Engine Misfires

An engine misfire can occur because of combustion shortages. A faulty ignition module is one of the main factors for incomplete combustion. (1)

3. Stalling

The engine should get sparks. Otherwise, it can lead to various problems such as stalling. A faulty ignition control can interfere with this process.

4. Unable to Power Up Accessories

Usually, when your vehicle is in a Running position, all the other accessories will power up. Right? However, if you are dealing with a faulty ignition control module, these accessories won’t power up after adjusting to the Running position.

5. Vehicle Starting Issues

A bad ignition control system can cause some starting issues for your vehicle.

About The Ignition Control Module

icm

Simply, ICM is a switch that turns the ignition system Off and On. There is a sensor located inside the distributor. This sensor sends a signal that can fire up the ignition coil inside the ICM and the process will produce enough energy for the spark plugs. Then this energy creates voltage for air/fuel mixture and timed combustion. Eventually, the ICM should control the spark timing accurately.

To sum up, ICM controls the ignition timing, the firing of spark plugs, and the ignition coil pack activities.

Tools Needed

To execute the ignition control module test, you will need some tools. Gather all of the required tools before starting the testing process.

Note: Apart from the above tools, you will need someone to help as well.

How Can I Recognize the Ignition Control Module?

We hope that from the sections above, you now have a good understanding of the ignition control module. However, if you are having trouble identifying the ICM, this section will help you immensely.

The location of the ICM can change according to the built year and the model. For instance, some vehicles come with a separate ICM; some vehicles come with an ICM that is controlled by the Engine Control Module, aka ECM.

car engine
Video | hoohoohoblin

Tip: An ECM unit is also called the Engine Control Unit(ECU) or the Powertrain Control Module.

However, before rushing into anything, first, find out whether you have a separate ICM or an integrated ICM. To do that, you would have to do some research. Usually, the ICM is located in the engine compartment or the distributor housing. From out of these two locations, you can find a small computer chip, which is the ignition module control. The image shown below will give you a better idea of it. (2)

car engine
Video | hoohoohoblin

3 Step Guide on How to Test Ignition Control Module with Multimeter

For this process, we will use a multimeter test. If you follow these steps correctly, it will take around 10 minutes to complete the testing process. So, let’s get started.

Step 1 – Check the ICM’s Current

First, place the black probe of the multimeter on the vehicle’s metal frame. The metal frame should be grounded properly. Otherwise, the experiment will fail. Then ask your helper to crank the engine. While the helper is doing that, you must check the different terminals. Place the red probe on each terminal. We use this simple experiment to check the current.

mechanic testing car ignition using a multimeter

If the current is traveling through these terminals, you will get a reading on your multimeter. However, if you do not get any reading that means you have to replace the entire ignition control module. You may check this guide for analog multimeter reading.

Note: While testing with the multimeter set it to either voltage mode or resistance mode.

Step 2 – Check the Spark Plugs Current

As you can understand, in the step above we check the ICM for current. If the current is flowing through the ICM, you can move on to Step 2.

In this step, we are going to test the ICM spark plugs. For this, you will need the 12V test light. Place the 12V test light into the terminals. While holding the test light, ask your helper to crank the engine. If the test light flickers while the helper cranks the engine, the spark plugs are working properly. Apply the same process to all the terminals.

However, sometimes, the multimeter won’t show any readings. So, then what? If you are not getting any current, follow the instruction of Step 3.

Step 3 – Recognize the Faulty Wires

You should follow this step only if you didn’t get any current in Step 2. Having said that, in this step we are going to check for continuity.

First, isolate the wires that have a break or burnt marks. Then set the multimeter to resistance mode. Now test the wires that go from/to spark plugs and the ignition control module. Remember, we are checking for continuity here. Therefore, if the multimeter shows an infinite reading, the particular wires are faulty. If the multimeter displays a zero reading, the wires are working properly.

Apply the same procedure to all the wires. You may have to spend some time, but you will be able to identify the faulty wires easily. After recognizing the faulty wires, replace them with new wires. However, if you are unable to complete the replacement process by yourself, don’t hesitate to get help from a professional.

Deeper Look at the ICM Circuit

During Step 3, you will have to check the wires that are coming out of the ICM. Right? However, most people struggle to identify those wires correctly. So, here is a visual aid for you.

car ignition parts

Pink Wire (A): 12V Power Circuit

White Wire (B): Ignition Control Signal

Black Wire (C): Engine Ground Circuit

White Wire with Black Stripe (D): Switching Signal

Note: As mentioned earlier in this article, depending on the build year and the model, the wires and locations may vary.

Wrapping Up

We hope that today, with this article, you were able to get a clear and decisive answer for how to test the ignition module with a multimeter. Always remember to follow our three-step guide properly. Don’t ignore any of these steps. For instance, some people jump straight to Step 3. They ignore Steps 1 and 2 completely. But, sometimes, if you follow Steps 1 and 2 accordingly, there is no need for Step 3.






References
(1) combustion – https://www.britannica.com/science/combustion
(2) computer chip – https://www.intel.com/content/www/us/en/history/museum-making-silicon.html

Video Reference

About Sam Orlovsky

b1d87d2ee85af3e51479df87928bdc88?s=90&d=mm&r=gI realized early on carpentry was a huge passion for me and I’ve stayed in the industry for over 20 years now. This gives me a unique ability to really be able to tell you what the best tools and recommendations are. I’m not only a carpenter but I also like machinery and anything to do with electrics. One of my career paths starting off was as an apprentice electrician so I also have a lot of experience with electrical products and anything related.