Difference Between ECM and PCM

An automobile engine features a part called the computing module (ECU). This part is responsible for controlling fuel supply, fuel injection, ignition, and even air management.

ECM and PCM are two modules that are used in ECUs. However, they are very different from each other.

Each of them carries out a different function in the ECU.

ECM vs PCM

The main difference between ECM and PCM is that ECM (Engine Control Module) is mostly used in older vehicle models along with TMC, for carrying out specific functions such as ignition timing, wastegate pressure, throttle position, and fuel injection timing whereas PCM (Powertrain Control Module) is used in relatively newer vehicle models and acts as one unit for controlling all the functions of the vehicle.

ECM vs PCM

The first ECM was created in 1939 by the company, BMW. This was for their 801 14-cylinder aviation radial engine.

It was made to manage and control various functions of the engine, along with another module called TMC.

However, as technology progressed, the module was only restricted to old models of automobiles.

Meanwhile, PCM is a newer module that works much more efficiently and on a larger scale as compared to ECM.

It carries out all functions of ECM as well as TCM while acting as a single unit of control. For this reason, it is used in newer models of vehicles.

It was first used in the 1970s but was not very efficient. Since then, many upgrades have been made for it to become the most efficient module in today’s time.

Comparison Table Between ECM and PCM

Parameters of ComparisonECMPCM
Full-FormIt is an acronym for Engine Control Module.It is an acronym for Powertrain Control Module.
LaunchIt was first used in 1939.It was first used in the 1970s.
FunctionIt carries out functions such as ignition timing, wastegate pressure, throttle position, and fuel injection timing.  It carries out all the functions regarding computing information for an engine.
NatureIt works along with the TCM.It works as a sole individual unit.
UseIt is used in older automobile models.It is used in newer automobile models.

What is ECM?

ECM is an acronym for Engine Control Module. This is essentially a part of the Engine Control Unit or the computing module of an engine.

Its primary function is to compute information for an engine to function as per the user’s commands. However, this is done along with the functions carried out by TCM.

ECM does not function alone. For this reason, it is mostly used in older automobile models.

The module controls and manages functions including ignition timing, wastegate pressure, throttle position, and fuel injection timing.

This means that it manages a series of actuators on an engine in order to make sure that it is performing efficiently.

The ECM read values through its sensors that are located in the engine bay. These values are interpreted using lookup tables which are essentially multidimensional performance maps.

Furthermore, the interpreted data is used to adjust the engine actuators, thus ensuring optimal performance.

The earliest design of an ECM was made in 1939 by the company BMW. It was made their car that features an 801 14-cylinder aviation radial engine.

However, it was not very efficient then. Many upgrades have been made to the module since it was first created.

Although, this meant that ECM would only be outdated by newer modules that function without TCM.

What is PCM?

PCM is an acronym for Powertrain Control Module. Like ECM, it is an essential part of the ECU.

However, it carried out all the functions of controlling an engine, even those that the ECM carries out. It does so as a single unit of control.

This means that it does not need TCM for functioning. For this reason, it is used in newer models of vehicles.

There are more than 100 factors that a PCM controls and manages in an automobile. This is done through sensors that are located in different parts of the car.

Like ECM, these are not confined to the engine bay. These sensors interpret data and manage the actuators, so the engine shows its highest possible performance.

However, the module has a very high failure rate.

The earliest design of PCM was used in the 1970s. Later, in the 1980s, this module grew popular among various automobile enthusiasts.

Then, it was used in conjunction with the carburettors that were electronically controlled, along with the lockup torque converters.

However, this design was not the most efficient. Since then, many upgrades have been made to this design. Nowadays, most new models of vehicles use PCM for engine management and control.

Main Differences Between ECM and PCM

  1. ECM is an acronym for Engine Control Module whereas PCM is an acronym for Powertrain Control Module.
  2. ECM was first used in 1939 whereas PCM was first used in the 1970s.
  3. ECM carries out functions such as ignition timing, wastegate pressure, throttle position, and fuel injection timing whereas PCM carries out all the functions regarding computing information for an engine.
  4. ECM works along with the TCM whereas PCM works as a sole individual unit.
  5. ECM is used in older automobile models whereas PCM is used in newer automobile models.

Conclusion

ECM and PCM are two modules that are used in an ECU. They are often confused to be the same things, even by mechanics at times.

However, they are not interchangeable.

The most notable difference between them is ECM was used in older automobile models along with TCM whereas PCM is used in newer automobile models as a single unit, without the TCM.

Moreover, each of them carries out various functions differently. ECM is only responsible for specific functions such as ignition timing, wastegate pressure, throttle position, and fuel injection timing.

The rest of the management functions of the engine are carried out by the TCM. On the other hand, PCM carries out all the control functions of the engine, including those that ECM and TCM carry out.

References

  1. https://www.jstor.org/stable/44736558
  2. https://www.sae.org/gsdownload/?prodCd=2011-36-0244
AskAnyDifference HomeClick here
Search for "Ask Any Difference" on Google. Rate this post!
[Total: 0]
One request?

I’ve put so much effort writing this blog post to provide value to you. It’ll be very helpful for me, if you consider sharing it on social media or with your friends/family. SHARING IS ♥️

Subscribe
Notify of
guest
0 Comments
Inline Feedbacks
View all comments