What is Powertrain Control Module?
The PCM is known as the brain of the vehicle. The PCM is also known as the engine control module (ECM). It is a self-propelled control system installed in your car.
The main function of the PCM is to collect data from different parts and sensors of your vehicle engine. After collecting the data, it uses data to produce the desired power and efficiency of the vehicle by controlling the engine’s spark and fuel.

Symptoms of a bad PCM
The probability of permanent failure of your car’s powertrain control module is very low in the latest vehicle models, but it may fail with time. As the powertrain control module goes bad, it generates one of the below-given symptoms:

1) Check Engine Light
The check engine light is one of the major symptoms of a bad PCM or ECM. However, this light may illuminate due to many other problems in your car. For example, issues with wiring, MAP sensor, IAT sensor, or engine overheating may also trigger check engine light.

2) Reduced Engine Performance
The bad performance of your car’s engine can be the reason for a bad powertrain control module. As the powertrain control module goes bad, it doesn’t properly control the fuel and the spark timing. When the fuel and spark timing disturb, this results in poor performance of the engine.

3) Issue in Shifting Gears
A problem in gear shifting is also one of the common symptoms of PCM failure. The PCM controls the functions of the transmission system and the engine of your car. Thus, the issues with the powertrain will indirectly be the issues with your car’s powertrain control module.

4) Issues in Starting
It is the job of the powertrain control module to ensure that every component it controls is working properly. Timings of the ignition are one of these tasks. When the timing is off, the spark plug doesn’t ignite the air-fuel mixture.

5) Misfires
If your car often backfires or misfires, then it needs a proper check-up by a professional. In the service centers, the professional will find the trouble codes and will let you know the exact issue with your car.

6) Failed Emission Test
A healthy powertrain control module ensures the minimum emission of exhaust gases and improves engine performance. However, when the PCM goes bad, it doesn’t control the emission efficiently and increases the emission rate.

7) Poor Fuel Economy
A reduction in fuel economy is often a sign of a bad PCM. When the powertrain control module goes bad, your car couldn’t be able to detect exactly how much fuel it has to burn in the combustion procedure.

8) Code Errors related to PCM
The bad PCM related trouble code is a most common symptom. A trouble code is created in your car’s computer whenever a car faces an issue. Use a proper OBD2 scanner to read the code. If the code is related to the PCM, then you are lucky that you detected the proper issue at once.

Causes of a bad PCM
1) Engine overheating problems
2) Manufacturing Issues
3) Electrical Issues
4) Physical Damage
5) Faulty sensors

--- Time Stamp --
00:00 - Introduction
00:37 - Powertrain Control Module Function
01:17 - Symptoms of Bad PCM
05:16 - Causes of Bad PCM

Disclaimer:
This video is just for educational purposes only. We are not in the auto repair business nor publish automotive service manuals. This video is not reviewed or authorized by any vehicle manufacturer. This video is intended only as general guidance. Every system is slightly different, so refer to the owner’s manual of your vehicle for any specific information about your model. Remember that only proper service and repair procedures will ensure your car's safe and reliable operation.

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For a Deep Learning about PCM, Check this article: https://mechanicalboost.com/pcm/