The system that monitors power train gears (engine, transmission, drive shafts, differentials, etc) and make the gears to work together in order to keep vehicle moving efficiently is called Power Train Control Module, abbreviated as PCM.
If all gears are working properly then you improve the car to better shape but if any one gear starts to show problems then your vehicle will bear along with your pocket.
Below are the functions performed by PCM:
PCM acknowledges the input given by different engine sensors so that computation of fuel flow rate can be made. It provides correct amount of fuel flow rate to sustain an agreed fuel/air ratio right through the whole engine operational rate.
Secondly, PCM gives directions to fuel injectors so that injectors gauge the correct quantity of fuel.
Get the hint that when power train shows to have problems, its right time to substitute the PCM module in your car. In maintain a vehicle in good position, problems in PCM cannot be ignored. Don’t get worried that from where you will find another module.
Instrument Cluster Store is the right choice to find huge range of high quality, pre owned instrument clusters, and engine computers. Here, engine computers are available for every size and model. Replace a PCM when it first shows problem or PCM can affect your vehicle’s overall efficiency badly.
This shop had many distinct electronically parts that look like a personal computer more than a vehicle. Every vehicle manufactured from starting of 1990’s till present have small gear known as power train control module. This gear controls parts of vehicles and runs tests on them electronically.
Now we should know how PCM module looks like so that we can identify it easily. This module is a printed circuit board resided in heavy duty case that can survive through the severest temperatures which are usually experienced within the vehicle’s engine.
The module keeps sending the electronic signals to all the gears of engine and keeps testing the temperature and airflow around them. It does this to check if operations are carried out properly or not. If some gear does not work properly then module switches on the check engine light on vehicle’s dashboard.
96-04 Dodge Caravan – Chrysler Town Country PCM ECU ECM- Programmed to your vehicle!
The module scans the camshaft, coolant levels, crankshaft, ignition and valve timing, air intake and the turbocharger gears in a car. It automatically normalizes the ratio of air to fuel used in engine. Besides, it also controls the idle speed so that vehicle keeps operating at highest performance level.
The module works in combination with catalytic converter to lessen the amount of pollutants produced from engine’s exhaust and retain the vehicle speed when feature namely cruise control is switched on.
A special diagnostic code is created by PCM. This code is based on vehicle’s gear which is not working. This not working properly gear is then read by electronic diagnostic tool used by mechanics.
Readin a code is easier way to find out the problem in vehicle than to replace the piece. Another bonus benefit is that when new gear is added for purpose of maximizing efficiency and performance, some modules can be programmed again.
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Even though all the connectors are resided at same place i.e. beneath the dashboard on driver’s side, different models of cars manufactured in different years might have different and separate kinds of connectors to plug into a diagnostic reading tool. Memory of PCM to save the previous diagnostic codes can also differ.
PCM in cold temperature carries out those set of directions that are already determined. These directions are carried out till engine comes back to normal temperature range. After engine comes back to normal temperature range, module again starts operating normally.
Another important thing to remember is that module doesn’t work if battery is disconnected. If battery remains detached for more than ten minutes, all the codes are automatically deleted from memory of module.
There is no code to give us hint when module is facing problem and not working properly. The only hint of failure in operating is that it starts to generate codes for gears that are faulty.
Following are the functions that PCM performs in relation to OBD II Diagnostics:
• PCM executes micro processor based on self diagnostics to make sure correct operations of PCM are carrying out and that OBD II diagnostic data in memory is storing properly.
• It carries out on-board diagnostics instantaneously and aware the driver by revealing MIL when there is an error.
• It executes power train control functions to lessen the emissions and assemble the OBD II policy when open loop functions are carried out at starting time.
• It executes power train control functions to lessen the emissions and assemble the OBD II policy when closed loop is in control at normal operations.
• It executes microprocessor based self diagnostics to make sure the proper operation of PCM and OBD II diagnostic data in memory is safely storing.
Below are the self diagnostics carried out by PCM:
PCM validates the checksum of program memory in ROM along with task and right adaptation.
It executes read and write test of RAM cells so that error free memory is identified.
It carries out operations in CPU, peripheral devices to validate the proper functions of processor. A/D convertors, watchdog timers, and registers are including.
It checks the stored vehicle data and validate that data is not tainted and is in limits of vehicle operations.
It carries out on board diagnostics at correct time and alerts the driver by revealing the MIL when there is an error. This is done by combining diagnostics with vehicle control functions.
The diagnostics are rated according to priority levels between 1-8 or 9 scale. The utmost priority tests are carried out in every 1 millisecond. The next priority level tests are carried out in every 5 milliseconds, 10 milliseconds, 20 milliseconds, 50 milliseconds, 100 milliseconds, 200 milliseconds, 500 milliseconds, and 1 second.
How to confirm if priority level tests are highest? So the highest priority level tests are those that effect safety and emissions to a high degree according to OBD II policies. Oxygen sensor and check on fuel trims during closed loop operations of vehicles are including.
The next priority test level is check on interrupt timers and watchdog timers. The next priority tests are sensors which includes EGO sensor, Throttle position sensor, Misfire detection, MAP sensor, Engine RPM sensor, MAF sensor, Crankshaft position sensor, and Engine coolant sensor.
The more next priority level tests are EGR intrusive tests, Catalytic converter’s secondary air, and canister purge, fuel level sensor, pedal actuator, and ignition timer. And the next priority checks are self tests at particular periods.
PCM executes on board diagnostics instantaneously. PCM is interrupted by instantaneous time’s scheduler during the performance of normal vehicle control operations. This is the time period when PCM saves current state of vehicle and carries out the diagnostics.
The whole process is completed in 100 microseconds. After this PCM comes back to normal vehicle control functions. For every priority level test, same procedure is repeated. PCM gives 15-45% of its time to diagnostics and rest of the time n performing and carrying out normal vehicle control functions.