Testing the powertrain control module (PCM) on your car is one of the most important things you can do to keep it running smoothly. A bad PCM can cause all sorts of problems, from poor performance to a complete failure of your vehicle. In this article, we will teach you how to test PCM with a multimeter using easy-to-follow steps. We will also answer some common questions about PCM testing so that you can feel confident in your ability to troubleshoot this important component!
What is PCM and Where Is It Used?
The main purpose of a PCM is to control and monitor engine functions. It does this by constantly monitoring various sensor inputs and making adjustments to keep the engine running at peak efficiency.
The PCM is also responsible for controlling other systems in the vehicle, such as the transmission, climate control, and even the audio system. In newer vehicles, the PCM is often referred to as the brain of the car because it controls so many functions.
In addition to that, PCM is the most common form of digital audio and is used in CDs, DVDs, Blu-ray discs, HDTVs, and many other consumer electronics devices. PCM is also used in professional audio applications such as recording studios and live sound reinforcement systems.
Testing a PCM with a multimeter can be a bit tricky because there are so many different variables that need to be considered. In the next section, we’ll go over some tips on how to get the most accurate results when testing your PCM.
Keep in mind that a multimeter is just one tool that can be used to test a PCM. There are other specialized tools that may give you more information or provide more accuracy. However, a multimeter is a good all-purpose tool that can be used to test many different types of electronic components. [1]
How to Test PCM With a Multimeter
Now that we know what a PCM is and what it does, let’s talk about how to test one with a multimeter.
Visually inspect your PCM
Maybe the answer to your problem is staring you right in the face. If you see any cracks, discoloration, or other damage to the exterior of your PCM, it’s probably not working correctly and will need to be replaced. However, even if you don’t see any visible damage, it’s still a good idea to test the PCM to be sure.
When doing a visual inspection, it’s best to make sure that all of the connections are secure too. Loose connections can cause inaccurate readings or no reading at all.
Checking the battery charge with a multimeter
One of the first things you should do when testing your PCM is to check the battery charge. A multimeter can be used to test the voltage of the battery, and this will give you an indication of how much charge it has. Usually, the battery is actually the culprit for various PCM issues.
To test the battery voltage, set your multimeter to the “DC Voltage” setting and set the range to either 15V or 20V. Then, remove the battery plugs from the PCM and touch the multimeter probes to the exposed battery terminals (touch the red lead to the positive terminal of the battery and the black lead to the negative terminal). You should see a reading of around 12 volts if the battery is charged and the engine is switched off. If it’s lower than that, it may need to be recharged or replaced.
Once you’ve confirmed that there’s enough charge in the battery, you can move on to testing other aspects of the PCM. [1], [2], [3]
Code scan it with OBD II scanner
If your engine is having trouble starting, or if it’s running rough, one of the first things you should do is run a code scan. This will help you to identify any codes that have been stored in the PCM, which can point to a particular problem.
To run a code scan, you’ll need an OBD II scanner. These are relatively inexpensive and can be bought at most auto parts stores.
Besides that, you will also need an adapter that connects the OBD scanner to the PCM. The type of adapter you need will depend on the make and model of your vehicle.
Once you have all the necessary equipment, follow these steps:
- Start by turning on the OBD scanner and connecting it to the PCM using the adapter.
- Select the “Code Scan” or “Diagnostics” function on the scanner.
- Follow the prompts on the screen to begin scanning for codes.
- Once the scan is complete, a list of codes will be displayed on the screen. These codes can be looked up in a code book to identify what they mean.
Different codes will point to different problems, so it’s important to note any codes that are displayed. Once you have a list of codes, you can start troubleshooting the issue. [1], [2], [3]
Inspect the wiring
Sometimes, the problem is not with the PCM, but with the wiring. Check all of the connections and make sure they are tight. If you see any corrosion or damage, that could be the issue. You can do this with a multimeter as well!
Just set it to the ohm setting and touch the probes to the wires. If there is no continuity, that means there is a break in the wire.
Then, check all of the fuses. Most cars have a fuse box under the hood, and there may be another one in the cabin. Look for any fuses that are blown and replace them.
If you still can’t figure out what’s wrong, it’s time to take your car to a mechanic or dealership. They will have specialized equipment that can diagnose problems with the PCM. [1], [2], [3]
Replace your PCM
Finally, if you’ve tried everything and the problem is still with the PCM, you’ll need to replace it. This is a pretty big job, so you need to take the task seriously. The good news is that PCMs are available from a number of different manufacturers, so you’re likely to find one that fits your car and your budget. Be sure to get the correct year, make, and model for your car.
Once you have the new PCM, it’s time for the installation. Again, be sure to follow the instructions that come with your PCM. You’ll also need to reattach any wiring or connectors that were removed when the old PCM was taken out.
Once everything is in place, turn on your car and see if the problem is fixed! [1], [2], [3]
FAQ
What causes PCM failure?
There are many factors that can lead to PCM failure, but the most common cause is overheating. When the PCM overheats, it can cause the solder joints to crack and break, which will eventually lead to a complete breakdown of the unit. Other causes of PCM failure include physical damage (such as being dropped or hit by a foreign object), water damage, and electrical shorts.
How do you know if a PCM relay is bad?
There are a few signs that indicate a bad PCM relay. The most common symptom of a faulty PCM relay is engine stalling. Other symptoms include issues with the fuel pump, headlights, and power windows. If you suspect a bad PCM relay, testing it with a multimeter is the best way to confirm the issue.
Can I test the PCM with a multimeter?
Yes, you can test the PCM with a multimeter. Actually, it’s a tool that can come in handy when diagnosing engine problems. Just be sure to follow the general safety guidelines when working with electrical components in your vehicle.
How do I test my PCM?
The best way to test your PCM is with a multimeter. You can use a multimeter to test the voltage, amperage, and resistance of your PCM. By testing these values, you can determine if your PCM is working properly.
How does a PCM get power?
The PCM gets power from the battery through two fuses. One fuse supplies power to the PCM on all the time, while the other only supplies power when the ignition is turned on.
Useful Video: AUTOINFORM ONLINE MAGAZINE: HOW TO DO PCM TESTING ON VEHICLES
Conclusion
This concludes our guide on how to test PCM with a multimeter. Testing PCM is important because it can help determine whether or not your car is running properly. By using a multimeter, you can test the PCM for issues that may be affecting your car’s performance.
We covered the basics of what you need to know and some helpful tips. Don’t forget to perform a visual inspection of the PCM before testing. And if you are going to replace the PCM, make sure to get the exactly right model for your vehicle. We hope this guide was helpful and you were able to successfully test your PCM. With the right tools and knowledge, testing PCM is easy and can save you time and money in the long run. Thanks for reading!
References
- https://electrouniversity.com/how-to-test-pcm-with-multimeter/
- https://handtoolsforfun.com/how-to-test-pcm-with-a-multimeter/
- https://www.solopcms.com/blog/how-to-test-a-pcm-complete-guide/