What is a PCM, ECU, Immobiliser or a engine computer ?


Jan 14th, 2019

What is a PCM, ECU, Immobiliser or a engine computer ?

There are several components which are combined together so as to ensure the effectiveness of an automobile car. Most users do not know these parts because they are only concerned about the work of the vehicle. However, knowing some of the parts would keep the user informed about the vehicle as well as how to maintain it appropriately. This content would provide essential information about the power control module of a car which is also referred to as the major component. You should however read the entire content to be well informed.
The PCM otherwise known as the Power Control Module of your car is a critical automotive component or a combined control unit. Just like the human brain, which controls and also coordinates the different functions as well as activities of the entire body, PCM acts as the brain of your automobile system, it controls and also coordinates the functions of the various sub-system of your car.

Usually, the PCM consists of two sub-systems which are the engine control units (ECU) and Transmission control units (TCU). The major 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 cars. The TCU or Transmission control module takes inputs from the engine sensors or TCU to change the gears for the optimum engine performance thereby fuelling the efficiency of your cars.
The Power Control Module gets inputs from the sensors which are spread around the car and which gives necessary information related to the engine management as well as performance. The other subsystems controlled by PCM include the Fuel injection, Fuel emission, Automatic transmission, Anti-lock brake system etc.
As earlier stated, since the Power Control Module controls the different subnets 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 would understand what the signal gives and would take appropriate corrective measure so as to rectify the problem.
For instance, if there is a problem with the transmission system of your car and this problem has resulted into a high transmission temperature, the CPU will indicate that the temperature is high. Obviously, you will get the best transmission cooler which is suitable for your car make and model so as to fix the issue.
The efficiency of your PCM is very crucial to pick signals immediately from the subsystems whenever there is an issue and to alert the driver at the appropriate time. It is crystal clear that if the brain does not function appropriately, the entire sub-functions properly in the human body can be disrupted. If PCM does not function appropriately, you won’t be able to observe the faults or damages which has occurred to your vehicle, also the different sub-system of your car will not be able to communicate appropriately with one another and this can result into a serious damage to your cars.
However, there is a specific duration within which everything in this world can exist, the same is applicable to your Power Control Module. Your PCM can be damaged as a result of several factors, once you get to know the causes of a bad Power Control Module, the best thing is to prevent the damage. Some of the things which can damage a PCM include wear and tear, thermal stress, corrosion etc. The PCM can also be exposed to corrosion as a result of water, this should be prevented because it will affect the longevity of the PCM.
Additionally, PCM can be damaged as a result of 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 so as to fix the issue.
Symptoms of a damaged PCM
Whenever you get a “Check Engine” light, the first thing to do is to check the engine sib-system. If all the system is in perfect condition, the next possibility can be a damaged PCM. Apart from this, if you experience a trouble while starting or running your car, Poor engine performance or stalling of your car engines, remember these can be as a result of a bad PCM in your car.
Whenever you have problem starting your engine in the morning, it could be as a result of a damaged PCM or the engine control units. After a proper diagnosis of the other engine parts, if you are completely convinced that your PCM is damaged, the best thing is to replace your PCM either completely or partially.
In most cases, once the PCM is damaged, rather than replacing it completely, we can identify the damaged subset of the PCM and replace just the part rather than a complete replacement. The remaining units can be reassembled after which the PCM can be used again. However, it may be difficult to identify the damaged subnet for a complicated model of PCM. In such case, ensure you get help from a professional mechanic.
It is crucial for you to know that your car PCM is unique to your car and should be replaced with the PCM designed for the same make and model. If the PCM is not replaced with the appropriate model, it will not function properly thereby giving the least results.

Tips for replacing a damaged PCM
The first thing is to locate the PCM of your car, the PCM of some models of car can be buried under other components. Then disconnect the terminal of your battery and then replace your new PCM, you can then replace the battery terminal after the replacement.
For some car models, after disconnecting the battery terminal, the PCM needs to go through a recleaning procedure. A small scan tool would be required to reprogram the PCM. In some models of cars, it may take some time for the new PCM to get adjusted to different subsystem and to have a complete control over the sub-systems. If you observe that the check engine lights are still on or you get a malfunction indicator after replacing your PCM, you should know that something is actually wrong. You should take your car to a mechanic immediately.
The health of your automobile power control module plays a crucial role towards the overall health of your car. For an effective functioning of your PCM, it should be maintained in an appropriate manner. You shouldn’t overlook any signal and if you are not able to diagnose the problem, you should visit a reputable mechanic.

Some engine management systems are part of complete immobiliser kits, especially the ones for vehicles manufactured after the year 2000, those kits can include different components like the vehicles key ( which has a reader hidden inside it ), a key reader which usually a black ring around the ignition barrel, BCM (body control module)... some of the mid 2000 jeeps like the WH grand Cherokee immobiliser  kits include the steering column.. the holden TK Barina you must supply the instrument cluster when supplying a complete second hand ECU kit. 

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