ECM vs PCM vs ECU what are the differences?

ECM vs PCM vs ECU – Although starting to move towards electric cars or at least hybrids, internal combustion cars will still be around for at least the next 50 years. This is especially true in developing countries or even poor countries. However, still, internal combustion cars should not be used carelessly without considering, for example, fuel efficiency, especially the problem of exhaust gas emissions. Therefore, modern ICE cars are now equipped with a sophisticated engine management system equipped with a computer. The computer turned out to have different names, some were called ECM, and PCM and some also gave the name ECU.

ECM vs PCM vs ECU what are the differences?

ECM vs PCM vs ECU
This is an example of an ECU for a car.

From personal experience with respect to this particular subject, we will have many variables involved in it. ECM, PCM, and ECU are actually devices that are intended for specific manufacturers only. Usually, production cars from Asia use the term ECU or engine control unit on the computer for their cars. Meanwhile, cars from America such as the manufacturer General Motors use the PCM or powertrain control module and others use the term ECM or engine control module.

Of course, this is just a general context comparison. It’s not like comparing them in the context of the details of the work done by the three. Because in that context it will be very different from what their experts should do. At least electronics experts will be able to discuss in detail this problem.

The ECM or engine control module is usually a car control provided for almost all of your car’s electronic devices or your car’s engine sensors. There is also the possibility that the car will have other computers to control such as power windows, air conditioning, and transmission, and each company has its own name.

Especially for the terms PCM or “Powertrain”, chances are that this computer will control several parts of the car. Some of the most likely to be controlled are the transmission and engine, including controlling power steering and fuel emissions.

The terms most used for computers in cars are ECM and ECU. For ECM or known as the electronic control module, which means that all parts related to the electronic system will be controlled by the ECM.

So now there is no need to be confused with these three different terms. The point is that all three are computers that are embedded in a car for the purpose of integrating the engine management system and the power transfer system.

Types of Car ECU

In a car today, at least have 7 types of ECU in each unit. In brief, you can read the seven types of ECU in the following table;

7 Types of ECU in Cars

NOECU TypesMore Information
1.ECMThis is a car that is specifically used to adjust engine performance to be even more optimal. ECM starts from starting, spark plugs work up to the cooling process.
2.TCMThe Transmission Control Module or TCM is a module that can only be found on automatic transmission cars. This is useful for adjusting the displacement and transmission moment according to the engine RPM as well as for driving.
3.PCMThis is a special module used to regulate the performance of the powertrain section. PCM will make it easier for you to ensure the flow of power from the engine to the running wheels so that it is always efficient.
4.BCMBody Control Module is a type of model that is specifically used to regulate the electrical performance of four-wheeled car components. BCM consists of lights, wipers, horns, and an entertainment system that is in the car cabin.
5.Airbag Control ModuleThe airbag control module is a special safety module whose job is to develop airbags in the event of a hard collision with the car.
6.HVAC Control ModuleThe HVAC module will provide the best control for automatic cab circulation. Of course, it will practically adapt to the weather conditions outside and inside the cabin concerned.
7.ABS Control ModuleABS Control Module is a module that is used for cars in accordance with the ABS technology brake system. Its purpose is to adjust the brakes so that they will not lock the tires or slip when on slippery roads.
There are 7 types of ECU in a car. It could be for cars that are more sophisticated or not common in society, will have more ECUs in each unit. So, please comment for additional ECUs that are not in the following table, to complete this information from us.

Now you know what an ECU is. What’s more, the ECU is not a completely new technology. Next, you need to know what the types are. There are several types of ECU that you need to know, including;

ECM or Engine Control Module

ECM stands for Engine Control Module. This is a car that is specifically used to adjust engine performance to be even more optimal. ECM starts from starting, spark plugs work up to the cooling process.

ECM vs PCM vs ECU

Kia Sportage – Engine Control Module (ECM) Repair procedures – Engine Control System. Picture: Kia Sportage Manuals

The automotive world continues to develop along with technological improvements. What is attached to today’s cars is clearly different from the technology that existed in previous cars. As a result, the car is even easier to use, efficient, comfortable, and environmentally friendly.

One of the technologies applied to the latest cars is the ECM or engine control module. With the ECM, the combustion system work on the car can be done automatically. Well, in this article, we will discuss the ECM function and how it works.

The ECM or engine control module is a circuit to control the performance of the engine in the car, specifically the engines in the fuel combustion system. It is a computer system that is integrated with other components of the car. With the ECM, the process of burning fuel can be done automatically.

You could say, the ECM function is the “brain” of a car. ECM regulates the performance of several car engines at once. The ECM also protects the engine if there is a disturbance in the vehicle.

When the car is experiencing interference, the connected sensor will immediately send a special signal. The signal is then received and read by the ECM. Well, from this signal the ECM then deactivates the vehicle system.

The function of the ECM on the car is very crucial. Without the ECM, the car will not even be able to run. Following are some of the main functions of ECM:

1. Determine the injection duration

With the ECM, fuel injection in vehicles can be done automatically. The ECM has several sensors that can send signals containing accurate data about fuel pressure.

From this data, the ECM will adjust the duration of fuel injection into the combustion chamber so that the combustion process can take place. This also affects the cause of the RPM up and down on the injection car.

2. Controlling ignition timing

In addition to determining the duration of fuel injection, the ECM also has the task of controlling ignition timing. This ignition is needed so that the fuel can be processed into powder for the car engine.

The ignition process cannot be done arbitrarily because it can affect the engine’s performance. For this reason, the ECM is added to the car so that the ignition timing remains appropriate.

3. Setting the machine when it is cold

There are times when the car has not been used for a while. As a result, the car engine becomes cold. A cold engine can be dangerous because it can make the car difficult to start.

Well, ECM can overcome this. With a cold starter, the ECM function can regulate the engine to keep working even in cold conditions. So, you can still start the car even though the engine is cold.

4. Maintaining energy to stay big

When the car is at low rpm, there is a possibility of engine detonation. This can happen because when the rpm is low, the engine power will decrease. The ECM prevents this from happening by maintaining large engine power even at low rpm.

5. Set the speed of the vehicle

In cars with automatic transmissions, the ECM also functions as a vehicle speed regulator. Different from manual transmission cars, automatic cars do not have a clutch that functions as a speed controller.

This is where the ECM plays a role, which replaces the role of the clutch to regulate the speed of the vehicle on an automatic transmission car. From this, it can be seen that the ECM function in a car is very important. With the ECM, the car can become an automatic machine that makes your mobilization easier.

TCM or Transmission Control Module

Besides ECM, there is also TCM. The Transmission Control Module or TCM is a module that can only be found on automatic transmission cars. This is useful for adjusting the displacement and transmission moment according to the engine RPM as well as for driving.

ECM vs PCM vs ECU
This is an example of TCM on a transmission.

The transmission control module works in conjunction with the engine and the transmission to keep the car moving. As you move forward, the TCM is responsible for calculating the right time and place to change gears for the best possible driving experience.

Apart from these main responsibilities, this control module can also send OBD2 code to the car’s computer in case of a breakdown or other problem with the car’s transmission. These codes appear in the form of a check engine light on the dashboard. The check engine effectively warns you that something may not be right under the hood.

As it provides an important link between the transmission system and the engine, TCM is definitely an essential part of your driving experience. Without a properly functioning module, your car won’t be able to change gears when you need it. This, of course, can eventually lead to not only a subpar driving experience but also serious mechanical problems that require expensive repairs. These timely changes also help increase the overall efficiency of the vehicle, so you can get a better distance from every gallon of fuel you add to your tank.

Manufacturers design TCM to improve the gearshift quality in your transmission system. This means switching between gears is a smoother and easier process that is easier on gears. Your gears won’t suffer as much wear and tear, keeping your transmission in better shape for longer.

In addition, the ability of parts to send codes to the car’s computer serves as the best way to identify transmission problems before they go wrong. It can also help prevent serious damage and costly and time-consuming repairs in the future.

Signs of a Damaged Transmission Control Module

How SCV Works
This is the TCM that is having problems. Image source: Complete Car

Finding a problem with the transmission control module is essential to prevent further damage to other critical parts of the vehicle. Fortunately, we’ll find it very easy to spot problems with this section. Some of the most common signs of a bad transmission control module include:

  1. You have difficulty downshifting when you slow down, stop, or try to downshift manually.
  2. You have difficulty shifting gears when trying to accelerate or trying to shift manually, which can cause acceleration delays.
  3. Transmission is difficult for us to move to a neutral position.
  4. Your transmission shifts into neutral or into another gear on its own.
  5. There is a delay when you try to shift from one gear to another.

If any of these symptoms sound familiar, you may be experiencing a problem with your transmission control module. As soon as you encounter these symptoms, it is important to have the car checked by a repair shop.

Problems with your transmission control module could result in not being able to shift gears properly which could result in accidents and injury. Also, driving with the wrong transmission control module can cause permanent damage to the cables in your transmission.

PCM or Powertrain Control Module

Next is the PCM or Powertrain Control Module. This is a special module used to regulate the performance of the powertrain section. PCM will make it easier for you to ensure the flow of power from the engine to the running wheels so that it is always efficient.

The powertrain control module or PCM is an embedded system designed to control various functions inside a car engine. Basically, it is a small computer that keeps the machine working properly. Now, one might imagine that a car computer should be the same as, say, the laptop or desktop someone uses at home. Maybe in principle, if you think so, then you are right.

Unlike a personal computer, a PCM is what we call an on-chip system. This means that the entire computing system, including the processor, memory, and supporting peripherals, are all made small enough to fit on a single small circuit board or chip.

A powertrain control module or PCM performs the same set of functions over and over, while general-purpose computers allow you to install software that allows them to perform a variety of different functions.

BCM or Body Control Module

ECM vs PCM vs ECU
Body control module.

Body Control Module is a type of model that is specifically used to regulate the electrical performance of four-wheeled car components. BCM consists of lights, wipers, horns, and an entertainment system that is in the car cabin.

The body control module or body center control module (BCM) on a car is a processor-based electrical power distribution center. His job is to supervise and control functions related to the car body such as car lights, windows or power windows, security systems, door locks and access controls, and various comfort controls. The central BCM also operates as a gateway for bus and network interfaces to interact with remote electronic control units or ECUs for other systems. Control of various loads comes directly from the remote ECU via CAN/LIN communication or directly from the central control module. Remember that BCM does not control any functions related to the engine.

One that has developed technology for this need is Infineon. Infineon has developed an excellent, scalable portfolio of new protected high side switches PROFET + 2 high side switches developed for 12V lighting systems and capacitive loads and High Current PROFET which will ensure system reliability with short circuit resistance.

They have a range of highly integrated products that combine multiple functions in a single device such as multi-channel switches in the SPOC and SPIDER families, and System Base Chips (SBC) for more functionality in less space.

Airbag Control Module

Next, the airbag control module is a special safety module whose job is to develop airbags in the event of a hard collision with the car. Surely this module is familiar to you, right?

In the airbag system, one of the important parts is the airbag control module. We can think of this as the brains of the airbag system installed in the car. This is the main hub to which all sensors and other components of the airbag system are connected. Including pre-tensioners on the car seat belts, collision sensors and frontal impact sensors, the airbags themselves, and other components. This module is like the motherboard and processor of a computer. But especially for airbag systems that receive data from one end, process and evaluate it, generate commands, and send command signals to each component. The airbag control module can save events about collisions. Meanwhile, it is sensors that detect and record data and information about collisions.

The airbag control module makes decisions based on information from sensors. The sensor transmits data to the airbag control module at all times. The module then analyzes and generates the most appropriate commands in response. The airbag system ECU will analyze the crash speed readings and impact area to decide whether the impact of the collision is necessary to inflate the airbag or not.

On newer vehicles, the airbag control unit will also generate a command to stop the engine. There are also those who cut off the supply of fuel as a precaution. The airbag control unit in some modern vehicles will also disconnect the car battery. Thus, the system disconnects the battery power for better safety purposes in the event of an accident.

The airbag control unit module can connect as many as six sensors to it in some vehicles. The control unit can also intelligently receive and compare the signals and information it receives from other sensors to evaluate when the airbag needs to inflate. The control module can also send signals to turn on the interior and hazard lights.

The core functionality of the airbag control unit is to protect passengers from rear and front impacts during a collision. Modern airbag control units use the SPEED platform approach as a new safety concept. For mass production, the computerized efficiency, increased safety and economical cost of the SPEED platform make it a much more reliable and better choice in manufacturing airbag control units.

HVAC Control Module

The HVAC module will provide the best control for automatic cab circulation. Of course, it will practically adapt to the weather conditions outside and inside the cabin concerned.

ECM vs PCM vs ECU
HVAC Control Module. Image Source: Amazon.com

HVAC Control Module is one type of engine control module in a car. The HVAC control module will be connected directly to the engine control unit or ECU in operation. Both will be interconnected with each other as long as the engine is running to ensure the AC system works properly and does not interfere with the overall work of the engine. This is one of the reasons why the HVAC control module is also very important for engine health.

The function of the HVAC Control module or AC control module is to control and regulate all functions of the AC system electronically. This module reads data from the cab and the exterior of the vehicle and uses that information to set up and adjust the air conditioning system. In this case, the need for the AC system will be to adjust the module in such a way that it is able to keep the cabin at the right temperature.

Symptoms of a Faulty HVAC Control Module;

1. Inconsistent cooling

2. Outdated software updates

3. Uneven distribution of air

ABS Control Module

ABS Control Module is a module that is used for cars in accordance with the ABS technology brake system. Its purpose is to adjust the brakes so that they will not lock the tires or slip when on slippery roads.

ECM vs PCM vs ECU
Image source: Clearmechanic.com

The ABS control module is a microprocessor that performs diagnostic checks of the vehicle’s antilock braking system. Furthermore, the ABS control module processes information from the wheel speed sensors and the hydraulic brake system to determine when to release braking pressure on a wheel that will lock and start slipping.

Anti-lock brakes have been available since the 1980s. As of 2012, ABS brakes are standard on all model vehicles, and later as they are an integral part of electronic stability control. The anti-lock system prevents slippage when braking and stability control intervenes to prevent slippage even if we don’t press the brake pedal.

The dashboard ABS warning light should flash for a few seconds each time your vehicle starts the engine. However, if the ABS light comes on while driving, it indicates that the control module has turned off, the wheel sensor has failed or another problem has developed.

On many vehicles, the brakes should continue to operate normally when the warning light is on, but the antilock function does not work. However, in some vehicles, braking capability will be reduced if the antilock system is not functioning, and stability control and traction control (on vehicles with this feature) may also be disabled. The ABS warning light usually triggers a trouble code that we can read with the diagnostic tool. This is very helpful for mechanics to find problems and solve them more quickly.

This Most Often Makes – ECM vs PCM vs ECU – Broken

The Electronic Control Unit (ECU) plays an important role as a computer that regulates the sensors in the car. It can be said that the function of the ECU is more or less the same as the human brain. If the ECU or the car’s computer is damaged, automatically no one will adjust the sensors in the car.

Then, what factors actually cause the ECU to be damaged?

ECM vs PCM vs ECU
ECU water damage.

According to ECU 2000 service experts, generally, the ECU is damaged due to usage factors.

“For now, it’s because of the age of use, yes. All electronic goods must have an age of use,” he said. According to him, the average ECU lifespan is 20 years.

In addition, according to him, another factor that can cause the ECU to fail is the treatment from the mechanics, which is often not compatible with the ECU.

“Many mechanics don’t want to learn to keep up with current car developments,” he said.

“They still use the old system, for example, jumper cables, there’s no gasoline, try to jumper to the pump, there’s a lot of it,” he explained. In addition, the use of a test pen on the ECU is also considered to be wrong, causing the ECU to be damaged. “One of them also includes playing a test pen, it actually makes it break,” he said.

Symptoms of – ECU vs ECM vs PCM – on Broken Cars

Every modern car, such as the one using the MPI system or the EFI system, is equipped with a computer known as the engine control unit or ECU or engine control module or ECM or PCM. Further, see the difference between ECU vs ECM vs PCM. But actually, the three functions are almost the same. We will refer to it as the engine control unit (ECU).

This computer communicates with a series of car electronic sensors and other components throughout the vehicle’s system. The information received from these sensors will be received by the ECU and then the ECU instructs the actuators that match the sensors to run the system. Therefore, if the ECU is damaged, it is almost certain that the car has a major problem and the engine may not start at all. So, this time we will discuss signs of a damaged car ECU so that unpleasant things don’t happen.

ECM vs PCM vs ECU
Check engine is ON due to ECU or ECM or PCM damage.

If your car’s ECM is faulty, it’s a sign that you have a lot of problems. Since the ECM is the part that controls most of the vehicle’s functions then if it is damaged then you cannot operate your car properly. The following are signs of a faulty car ECM and it is hoped that after recognizing these signs you can at least take the car to a trusted repair shop for repairs.

1) Check Engine Lamp On

The first sign is the light of the check engine lamp on the dashboard. There are many reasons why the check engine light is on. But obviously one of the reasons the check engine light is on is because the ECU is faulty. As explained earlier that all sensor controls point to the ECU for data management. Therefore, it is very possible for the ECU to be damaged and marked by such a sign.

There are actually encouraging things even though the check engine lamp is on. Is that what is damaged is, of course, not the engine directly as well as having to disassemble the engine due to engine overheating for example. That means the costs incurred are not too large. However, it is the complexity of detecting which can be a big problem for the mechanics working on it.

2) Decreased Fuel Efficiency

The second tent is fuel efficiency which has decreased even drastically. When the engine control unit is damaged, the ECU cannot manage the combustion process in the combustion chamber properly. This causes the fuel injector to spray too much fuel every time. It doesn’t matter whether the engine is idling or accelerating. So this condition will clearly reduce the fuel efficiency of the car. As a result, it will waste fuel and force you to go to the gas station as often as possible.

3) Engine Stops Suddenly or Engine Stalls

The third sign is that the engine stalls or the engine suddenly stops or dies. Most people think that the engine stops suddenly is the result of running out of fuel. This thinking is true. However, a car ECU malfunction can also cause the engine to stop suddenly. Sudden engine shutdowns don’t happen regularly but usually do. This depends on how badly damaged the car’s ECU is. Therefore, it is better if the engine stops suddenly you take the car to a repair shop for further analysis.

4) Engine Not Starting

The fourth sign is the engine will not start. If at the previous sign the engine is running but occasionally turns off suddenly, at the fourth sign the engine really doesn’t want to start.

If your car won’t start – even though the starter motor is working fine – it is very possible that your car’s ECU is faulty. But remember the car does not want to start there are also many causes. But the ECU broke one of them. Modern engines rely on electronic data from the ECU every time the engine starts. If the ECU cannot provide data to the actuator, the engine will not start.

5) Weak Engine Performance

The last sign is weak or declining engine performance. The computer cannot set the exact timing of fuel injection into the engine. In addition, the flow of air from outside to the combustion chamber is also disturbed. It’s perfectly possible to drive a car with this kind of marking but it looks like you can’t accelerate like you normally would. When the gas pedal to open the throttle body valve is pressed, the car’s acceleration is not as fast or even unwilling as usual.

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