How To Test An Ignition Control Module With A Multimeter

(Last Updated On: March 15, 2024)

The ignition control module is a part of the ignition apparatus. It regulates the electrical current directed to the ignition coil to create the perfect voltage. This, in turn, permits the spark plug to ignite the fuel blend.

The ignition system makes a vehicle burn fuel into a small flare-up to generate power. If done incorrectly, power is likely to drop while emissions increase. As a result, ensuring that your vehicle’s ignition control module is in proper working condition is critical because poor handling and management could impair the performance of the ignition system. 

Negligence could also lower fuel efficiency while increasing unpleasant and toxic emissions. Read on to learn how to test an ignition control module with a multimeter. 

What Is An Ignition Control Module (ICM)? 

The ignition control module (ICM) collects information from a prompting device to establish a car’s base ignition timing. The prompting gadget is usually the camshaft position sensor or crankshaft position sensor. The right timing determines the health and performance of your vehicle’s engine. 

The complexity of an ignition system varies based on the make and model of the vehicle. For example, the ICM only regulates ignition timing on lower revolutions per minute in some cars. Having a good understanding of how the ignition system operates helps you determine how the ICM works.

Signs of A Bad Ignition Control Module

To diagnose ICM problems, watch out for the following signs. 

Temperature Issues

If your ICM has problems, then it’s likely to overheat. The car will be running only to lose power suddenly due to the increased temperatures in the engine. When the engine cools, the vehicle will start and continue running until it starts overheating. 

Acceleration Problems

The car might jerk, vibrate, or even shake when you press the gas pedal. You may experience insufficient power or hesitation when you attempt to accelerate. 

Failure To Start

The engine may crank but not start. You may have to make several attempts before starting the vehicle. Often, it will lose power suddenly after cranking. 

Other signs include:

  • Check engine light is on
  • Engine is misfiring
  • Stalling
  • Rough idle
  • Poor engine performance
  • Poor fuel consumption

How To Test An Ignition Control Module With A Multimeter


To test the ignition control module, you will need the following tools.

  • A multimeter
  • A wiring diagram of your car
  • Wire piercing probes
  • An assistant

Read more: 5 Best Multimeters For Automotive [2022 Review]

Step-by-Step Guide

how to test igntion control module with a multimeter
Knowing how to test ICM will help you avoid bad experiences when driving.

Step 1: Identify Where The Ignition Control Module Is

The ignition control model is based on the distributor housing. Sometimes it can also be fixed on the engine compartment’s side. 

Step 2: Test for Spark

  • Pull out one plug from the spark plug.
  • Place an old spark plug at the end of the plug boot.
  • Put the car’s spark plug at the top of a metal surface on the vehicle’s engine.
  • Crank the car’s engine and check for any sparks that may come out of the connected old spark plug.
  • If no sparks appear, there is a problem with the ignition.

After this step, you will need to use a multimeter in the subsequent processes. Ensure your meter is in proper working condition to guarantee accurate readings and eliminate errors. 

Step 3: Test the Coils for Voltage

Coils come with negative and positive terminals. Here is how to execute this step.

Test for voltage in the car coil’s positive terminal with the ignition key turned on. You will need to place the red lead of your multimeter on the coil’s negative terminal and the black lead on the positive. Leave the ignition key at the “run” position. 

The multimeter should read the voltage on the battery’s positive terminal. If there is zero voltage, your ignition wiring circuits or switch have a problem. 

Read more: Voltmeter vs. Multimeter: Which One Should You Choose?

Step 4: Find the Positive Ignition Modules Wire

  • Identify the positive ignition module wire.
  • Ensure the vehicle key is on the “run” position without starting the engine.
  • Use your multimeter’s red lead to pierce the vehicle’s positive ignition module wire. The wire will have a battery voltage reading. However, if there is no reading, check for possible open circuits between the ignition switch and wires. 

Step 5: Locate the Negative Ignition Module Wire

  • Identify the negative ignition module wire.
  • Use your multimeter’s red lead to prick the vehicle’s negative ignition module wire. 
  • Remove the vehicle’s distributor cap but leave the spark plug wires intact.

Rotate the distributor shaft with your hand, or do so by cranking the vehicle engine. Watch out for the distributor rotor while executing this process. If the distributor rotor doesn’t turn, there could be a fault either at the distributor gear or the distributor. The voltage reading on the multimeter should fall between the battery voltage and zero. If that is not the case, you should replace your ignition control module. 

Read more: How To Test Car Battery Amps With A Multimeter


1. What Would Cause An Ignition Control Module To Fail?

Often, ignition models fail due to heat. Many vehicles that have a recurring high-temperature problem often have the standard distributor. Due to wear, tear, and aging, the filling around the shaft wastes away and starts overheating. 

2. Can You Test An Ignition Coil?

Yes. Raise the hood and find the ignition coil in your car. After that, Pull out a single spark plug wire from the plug. Using insulated wires, grasp the spark plug to prevent electric shock. Hold the threaded section of the bare spark plug to a piece of metal in the vehicle’s engine. 

Take out the fuel pump relay to prevent the engine from starting. Still, a spark will be produced. Get somebody to crank up the car engine and watch for a blue spark. A blue spark shows that the ignition is functioning well. 

Orange sparks indicate a lack of sufficient power flowing from the ignition coil to the plugs. No sparks at all indicate that nothing is produced. Reinstall the spark plug after your findings. 


Testing an ignition control module with a multimeter is one of the fastest and most efficient methods. 

A car’s ignition module regulates the running and timing of spark plugs. When the spark plugs stop generating a spark or misfire, your vehicle’s performance will be affected. Various signs could suggest a faulty ICM. 

For example, the vehicle might fail to start, or you may notice an illumination in the engine lighting. The ICM is a sensitive element in your vehicle’s engine. It monitors cans and ensures that the spark is generated simultaneously with the ideal frequency. The combustion system will not operate effectively when the frequency is not correct. Always be on the watch out for any signs of a fault.

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