Cars,  Auto Engines

What Is A Powertrain Control Module (PCM) In Cars?

(UPDATING) You would know the fact that your car is designed with hundreds of complex subsystems in it. This complex system should essentially be operated and controlled in an efficient manner to give you a smooth and comfortable drive. Have you ever wondered how the smooth functioning of the interlinked sub-systems happens? This is made possible by your car’s powertrain control module.

The PCM or Powertrain Control Module of your car is a critical automotive component or, rather, a combined control unit. Like the human brain, which controls and coordinates the different functions and activities of the human body, PCM acts as the brain of your car, and it controls and coordinates the functions of the different sub-systems of your car.

The PCM, in normal cases, consists of two sub-systems: Engine control Units (ECU) and Transmission control units (TCU). The function of the Engine Control Module or unit is to ensure the optimum Engine performance by controlling a set of actuators on the internal combustion engine of your car. The TCU or Transmission control module takes inputs from the engine sensors or TCU to change the gears for the optimum engine performance and fuel efficiency of your cars.

The PCM gets inputs from the sensors, which are spread around the car and give information related to Engine management and performance. The other subsystems controlled by PCM include the Fuel Injection, Fuel emission, Automatic transmission, Anti-lock brake systems, and so on.

As already stated earlier, since the Powertrain module controls the different subunits of your car, whenever there is an issue with a subsystem or auto car part, it is the responsibility of the PCM to alert the driver. The driver will understand the signal and will take necessary corrective action to rectify the problem.

Powertrain Control Module PCM

Photo Credit:

Let’s take an example: If there is a problem with the transmission system of your car, because the transmission temperature of the system is high, the CPU will give the corresponding indication to you. Obviously, you will get the best transmission cooler suitable for your car model and use it to fix the issue.

The efficiency of your PCM is crucial to pick signals immediately from the subsystems in case of any issues and to alert the driver at the right time. It’s quite clear that if the brain does not function properly, all the sub-functions in the human body can be disrupted. If PCM does not function properly, you will not be able to construe faults or damages to your engine parts, and the different sub-systems will not be able to communicate properly with each other, and this can lead to serious damage to your cars.

However, everything in this world has an existence cycle! Your PCM can also be damaged due to different reasons. Once you get to know the causes of a bad PCM, It will be easy for you to prevent the damage. One of the reasons for a damaged PCM can be Wear and Tear, Corrosion, Thermal stress, etc. There are also chances of PCM getting exposed to corrosion by water.

The second reason for PCM damage can be due to short circuits and voltage overloads in the actuator circuits and solenoids in your car engine. In the case of short circuits, you can get the actuators repaired to fix the issue.

Symptoms of a Damaged PCM

Powertrain Control Module PCM

Photo Credit:

When you get a “Check Engine” light, the first thing to do is to check the engine sub-systems. If all the systems are perfect, the next possibility can be a damaged PCM. Other than this, if you experience trouble while starting or running your car, Poor Engine performance, or stalling of your car engines, remember these can be signs of a bad PCM in your car.

Problems while starting your engine in the morning could be possibly due to a damaged PCM and, most probably, the engine control units. After the diagnosis of the other engine parts, if you are completely convinced that your PCM is damaged, the only fix is replacing your PCM either partially or completely.

In most cases, once the PMC is damaged, rather than completely replacing it, we can even go for identifying the damaged subset of your PCM and replacing just the damaged part. The remaining units can be reassembled, and the PCM can be reused. Sometimes it becomes quite difficult to understand the damaged subset for a complicated model PCM. In such a case, it is always advisable to get the help of an expert mechanic to fix it.

It is very important that you know your PCM model is suitable for your car from the Engine make and model of your car. If the PCM is not replaced with the right model, it will not function properly to give the best results.

Tips to Replace Your Damaged PCM

Powertrain Control Module PCM

Photo Credit:

Locate the PCM of your car first; for some car models, it can be buried beneath other components. Disconnect your battery terminals first and then replace your new PCM. You can connect your battery terminals again after that.

For some car models, after disconnecting the battery terminal, the PCM needs to go through a relearning procedure. A small scan tool would be required to reprogram the PCM. For some models, it might take some time for the new PCM to get adjusted to the different subsystems and to have complete control over the sub-systems.

If the check engine lights are still on or you get a malfunction indicator after replacing your PCM, understand that there is something wrong. Don’t wait to take your car to a mechanic and get it checked.

The health of your PCM has a very important role in the overall health of your car. For your PCM to function effectively, it should be maintained in a proper manner. No signals or indicators should be overlooked. If you are not able to diagnose the problem don’t take chances, always consult an expert technician. Hope this article was informative, please share your comments.