How to Test ECM Computer [Step-by-Step]

The engine control module (ECM), is the computer that regulates engine performance. It also receives data from other sensors in your vehicle and monitors the fuel-to-air ratio and engine timing.

Are you tired of constantly dealing with computer issues in your electronic control module (ECM)? Do you want to ensure the optimal performance of your ECM computer?

Look no further as we bring you a comprehensive guide on how to test your ECM computer.

In this blog post, we will you through the several processes of testing your ECM computer.

how to test ECM computer

5 Ways to Test ECM Computer

1. Using OBDII Scanner

Testing ECM computers would be quite simple if you used OBD II. This is a scanner that can read engine codes and access vehicle data.

This scanner is used to inspect the engine of a vehicle and communicate any problems that may exist.

Connect the OBD II scanner tool to your vehicle’s diagnostic port to determine whether there are any faults in your vehicle via codes.

When an Onboard Diagnostic (OBD or OBD II) scanner displays codes, you will be able to identify if there is a problem with your computer and the cause.

However, to achieve a great result, you must understand those codes in order to repair your vehicle.

2. Visual Inspection

To test an ECM computer, you must first do a visual assessment of the ECM computer’s surroundings. The first thing you’ll notice when inspecting your auto computer is PINs.

If you see that the PINs on the ECM computer are fine and undamaged. The second step is to start the smell test on your vehicle computer – if your ECU computer smells more like burnt plastic, it signifies something is amiss or it’s not working properly.

You may need to open up the Engine Control Unit (ECU) board for further visual inspection to test the ECU computer. When you open the ECU board, take your time.

After you have opened the car computer board, you must inspect it for any broken components or corrosion on the ECU board.

If you find any broken components or rust after opening up the ECU board, the ECU computer will need to be replaced.

3. Battery Check

Check the voltage of your automobile battery with a multimeter both with the engine off and on.

Knowing the battery voltage can help you test the ECU computer because when the battery voltage is too low, the ECU cannot function properly.

When the battery voltage is low or incorrect, the sensors connected to your car’s ECU computer are unable to make the necessary adjustments. Therefore, when you drive on the road, you have to ensure your car battery is charged. 

If you measure 12.6 volts with the engine off and 13.7 volts with the engine running, your battery is fully charged.

However, if you read less than 12.6 volts with the engine turned off and 13.7 volts with the engine turned on, you should replace the battery.

4. ECM Swap

Only older vehicles benefit from this engine control module switch. Prior to 1996, automobile manufacturers produced vehicles with Onboard Diagnostic (OBD II) systems that did not require programming when installed.

If you have an ancient automobile produced before 1996, you may test the ECM computer with just a swap. All you have to do is first locate a replacement unit that matches the original component number.

And once you’ve installed the new unit and drive your vehicle through a complete drive cycle to confirm that the troubles you were experiencing with your prior unit do not reoccur.

If the faults do not recur after test-driving the car, it is a good indication that there was a problem with your initial unit. It’s critical to remember

Remember, this auto-computer testing procedure is intended for older vehicles with OBDII, not for newer vehicles.

5. The Elimination Process

This process is usually carried out by examining the car’s Inputs and outputs. This process o is a very useful approach to troubleshooting your automobile computer. It lets you know the present state of your car’s components.

The Ignition Switch, Fuses, Battery, and Sensors are all located in the car’s Input. Output, on the other hand, includes the Spark Plugs, Starter, and Injector. These are the components that must be tested in order to test a car computer.

The battery plays an important part in the removal of input processes. That is why you must first verify the battery voltage to the engine computer, as it supplies a suitable quantity of voltage via the ignition switch, sensors, and fusses since the battery produces voltage to the Engine computer via these input units.

After testing all of these output units, you will notice that some of them are not receiving the right signal, indicating that your car computer is defective or not functioning properly.

Can I Test My ECM at Home?

Yes, you can. Testing an automobile ECM computer necessitates specific expertise, equipment, and software.

So, if you have an adequate understanding of testing an ECM, program software, and tools, you may test your ECM at home without a problem.

And if you don’t know much about ECM computers or have no knowledge, you need first learn the ECM testing technique from a professional or an experienced individual.

An expert understands how to test an ECM computer properly. However, if you learn the technique, you should be able to test ECM on your own at home.

However, you need to keep this in mind. ECM computer is one of the most important components of a car.

Therefore, if anything goes wrong with the ECM computer during the test, it will need to be replaced. As a result, if you lack sufficient knowledge or experience, you should delegate ECM testing to a specialist.

Can ECM be fixed?

Repairing an ECM is dependent on the difficulties with your ECM. If your ECM computer’s software or code fails, you can try to fix it.

Read: How to Fix Flooded Engine


Your vehicle’s ECM computer testing is required to ensure your car performs well. Therefore, knowing how to test your ECU computer will help you determine the cause of your ECU failure as well as the usual signs of a failing ECU.

However, if you want to test your car’s ECU computer, you must have some specialist expertise and experience testing an ECM computer.