The Auto Engine Control Module and When to Replace It

example of a dodge cummins engine control module

The Auto Engine Control Module and When to Replace It

The act of diagnosing your auto engine control module, or ECM/PCM, can oftentimes be a long and involved process. When it comes to the control module, or electrical components in general, it is not always clear where your symptoms are originating from which can make it difficult to determine where you should begin in terms of testing and replacement. For many people, the engine control module can be perceived as a sort of enigma and when it malfunctions, it is common for many people to begin replacing parts with no clear direction in hopes that the problem gets solved. This confusion has a lot to do with the fact that the control module is responsible for many different areas within the vehicle so when something goes wrong, though the symptoms may appear to be an engine control module issue, the issue may actually elsewhere in the vehicle. This difficulty, however, can be mitigated by beginning to understand what it is that the control module does.

What does the engine control module do?

The term “brain” is one that is often used by mechanics and those in the industry to describe the vehicle’s engine control module and this term is an accurate representation of the module’s relationship with your vehicle. Similar to the all other vehicles, for example the dodge pcm communicates with other parts of the engine compartment in order to monitor and manage the way those components operate. In short, the ECM is responsible for ensuring that your vehicle is running properly and at its highest capacity. If something is not working the way that the ECM feels it should, then the control module will trigger a check engine light that alerts the driver of any potential issues. A trouble code can then be identified by using a scan tool to determine if the issue is a result of a bad PCM or something else.  These responsibilities make the engine control  unit an essential part of the engine management system and its performance vital to the overall engine performance of the vehicle.

example of a dodge cummins engine control moduleUnnecessary ECU Returns

Unnecessary returns are a common occurrence when it comes to powertrain control module (PCM) replacement, so a complete diagnosis should be your top priority. This means that a particular set of steps should be followed before making the decision to return or replace any parts. These steps involve a thorough inspection of the engine compartment and its wiring, as well as an examination of the components that are relevant to your vehicle’s symptoms. The PCM is connected to other components through an intricate wiring system, so if you suspect the control module to be faulty then you must check the other modules related to your symptoms as well as the according wiring. For example, if you are having an issue with the charging system, in addition to checking the engine control system , you will want to check components like the alternator or the battery and you will also want to check the wiring in between. This evaluation, though lengthy, is a necessary process to ensure that you are not needlessly returning and replacing parts that are actually fully functioning.

Why Did Your Powertrain Control Module Die?

The most common symptoms of an auto engine control module failure are due to environmental and external factors such as a fried internal circuit board due to exceedingly high voltage, or corrosion resulting from worn sealants. Issues like these, unfortunately, require a replacement unit altogether and, in addition to this, further diagnosis is required in order to determine what caused this to happen in the first place. An engine computer doesn’t often get burnt or corroded by itself so if the initial cause is not repaired, then you put your replacement ECM at risk.

In order for the engine computer to work, it must be supplied with the correct amount of voltage; too much voltage and it could cause a voltage overload and burn out essential components within the control module and short the unit altogether, not enough voltage and the module will not have enough power to operate at all. There are a few parts of your vehicle that are related to voltage and, if damaged, could put your engine control system at risk. The alternator, battery, spark plugs and wiring are a few of those components that could cause a spike in voltage. If this happens, the cause must be determined and repaired before replacing your engine computer. If you suspect that your engine control module is fried, you can check by removing the ECM and smelling the unit by the plugs. If the unit is fried, then it will give off a distinct scent like burnt electronics.

Water damage and environmental damage in general is always something that a car owner should be wary of. While rain or high temperatures will not damage your engine computer right away, wear and tear over a long period of time is something that is unavoidable. While your engine computer has multiple safe-guards in place to withstand the elements, these precautions are not meant to last forever so it’s important to take your own measures to protect your vehicle from harmful conditions. Keeping your vehicle away from moisture and out of the heat whenever possible are two ways to prolong the state of your vehicle.

Accurate Identification

After determining that a replacement PCM is required to repair your vehicle, you will need to correctly identify the unit that you require. It is not simply a matter of purchasing a unit from another vehicle of the same year, make, and model- each PCM is specific to the vehicle that accommodates it. For each particular vehicle there are dozens of different part numbers available. These part numbers are determined based on the particular specs of your vehicle and not many car owners are not aware of these specific details. Since each module looks identical to each other at first glance, the best way to determine the part you need is by getting the part number off of your original unit and purchasing that same one. It’s important to remember that reprogramming still needs to be done on the replacement module even if the part number is an exact match. If you are getting a replacement unit from another vehicle, then that means it has a different VIN programmed into. Any time you replace your powertrain control module, the VIN on it needs to match the vehicle that it is being installed in.

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Re-manufactured  engine control module ecm

When searching for a replacement ECM, you have likely come across the term “re-manufactured” or just “reman” and there is a difference between a re-manufactured unit and used unit. A re-manufactured ECM is an engine control module that has had all its faulty components replaced and they are also repaired to account for module failures that are typical among those types of units. For instance, if a particular component within the ECM is prone to fail, then companies will rebuild the unit in a way that reinforces that failure-prone area.

Replacement Tips

There are many companies that sell their modules completely plug and play so that installation can be done without the help of a mechanic or dealership. This process is very straight-forward and even car owners with limited experience can install the replacement unit by themselves. Once you have located the engine control unit on your vehicle, then all that needs to be done before installation is disconnect the battery. You can then plug your new unit into the wiring harness and reconnect the battery, then the vehicle can be started. After starting your vehicle, the ECM will engage in a relearning process where it will determine if everything in your vehicle is in working order. If the problem has been fixed, then the check engine light should remain off but if there are any additional issues to indicate a bad or failing component, then the check engine light will return after the cycle is complete. You will also want to complete a driving cycle by driving your vehicle at a speed of 35 miles per hour. For most vehicles, this driving cycle will be complete after an accumulated 50 miles have been driven, you can assume everything is functioning correctly and consider the problem solved and you no longer need a new auto engine control module if the check engine light does not return by then.

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