Of all the things that can go wrong with a car , electric system flaw are some of the most maddening . They ’re difficult to trace , often make out and go as they please ( enabling the grease monkey ’s favorite fuzz - out answer , " Could not replicate problem " ) and the symptom often appear far from the source . Sometimes , the symptoms of electrical problems do n’t even seem electrical in nature . And what are you supposed to do then ?
The engine control condition module might betray a few hints , even in name alone . Sometimes , the public figure of automotive constituent are so eccentric that we bury that some terms are completely intuitive and legitimate . " Engine control " is a no - brainer ; " mental faculty " mean it ’s electrical in nature . And if that ’s not enough to enlighten you , well , at least you were n’t the first to involve those questions . If you typecast " electronic control mental faculty , " or its better - known acronym , ECM , into the search arena , you ’ll be gently guided over to the ECU ( engine control unit ) page . And from there it can get perplexing , because there ’s a whole rat ’s nest of electric language to trace and pick through . Sometimes , the locomotive control module is at flaw for issues that would often be assumed to be " mechanical , " likeengine noiseor problems with the engine bunk swimmingly . So if you or your mechanic is going unhinged trying to figure out why your car wo n’t play , it might be because your car ’s ECM is just trite from doing it all , and needs some attention .
chance are , if you have relatively basic questions about your car ’s electrical functions , it ’s black market a common system or programme that ’s been in place since your car was built . ( We ’ll usurp , for example , you did n’t buy a second - or third - deal tune mutation compact work MegaSquirt tradition injectant to keep an oversizedturbochargerin line of merchandise – or that your car can perform everyday driving functions without changeless attention to a laptop computer light in the passenger seat . )
Functions of the Engine Control Module
The railway locomotive ascendence module basically insure the crossroad of theengine ’s necessary constituent to make push – fuel , air and arc . That sounds unproblematic , kind of in the same way an railway locomotive itself sounds simple if you wear it down into really basic term . But the ECM fulfil its considerable chore by constantly supervise a huge connection of sensors around the car to insure weather condition are within normal operating range . When something goes wrong , the ECM adjusts conditions or , if it ca n’t , the railroad car wo n’t lean properly or at all . When there ’s a job , the ECM stores a difficulty code so it can be diagnosed by a mechanic ( with a scanner specifically design for that use ) and trigger thecheck locomotive engine lightso the number one wood roll in the hay something ’s wrong .
Newer engine estimator systems also feature lightweight , low - monetary value memory systems that can be easily accessed by the dealership to fix programming issues and update specifications ( kind of like track down a system or software update on your computer ) .
One of the most recent task ( in the last 10 or so , anyway ) delegated to theengine computercame about only as automotive companies switched from mechanically skillful throttle ascendancy to electronic gas ascendance . Previously , when your pes made middleman with the throttle treadle , it was connected to a cable that went directly to the railway locomotive so the engine could decide how much fuel to interject , based on whether you caress the pedal , mashed it to the trading floor , or most likely , somewhere in between . Now , an electronic sensing element at or near the accelerator pedal sends a signal via electrical telegram to the engine management system , which evaluates your accelerator contact and then sends a sign to the engine to set fuel dosage .
Part of the ECM ’s take up - up subroutine is to calibrate the berth of the throttle at idle – in other words , remind itself , and the throttle , how the railway locomotive should run when it ’s not being throw any gas . This avail control and prevent an spotty idle . If all the sensors involved do n’t agree on the right placement , the computing gadget will send a signaling to the railway locomotive and transmission to run away in Limp Mode ( preclude the gadget driver from achieving gamy speeds that could get out of hand ) and also sends an alert to the instrument cluster . The idea is to permit it to run well enough to get to a mend shop , but not strand you on the side of the road .
The ECM also check that the car run across emissions criterion , by monitor and determine the fuel variety to assure the engine is n’t running too rich and emitting pollutants beyond the established parameters . And with all those sensors already in place , the ECM is often creditworthy for managing features like anti - skid brake system , cruise dominance and theft protection .
That sounds like a lot to keep straight , does n’t it ? So , on top of it all , the engine control module , unit , or what have you , incline through a recalibration test every prison term you turn on the car , just to check that signal do n’t get get over .
Engine Control Module Technology
The ECM is a computer , and features many of the same parts as the computer you have at home or at work . There ’s a microprocessor that receives , interprets and reacts to sensor inputs as tight as they fall out . And it ’s composed of hardware ( a pretty standardcircuit display panel ) that ’s encoded with software ( a program that tells the car how to run ) .
The railway locomotive control organization are n’t really designed by the auto maker – they ’re one of the components that ’s source and then customized . Only a handful of OEMs ( original equipment manufacturers ) make ECM systems for railcar . Each brand and type can be customise to fit the self-propelled manufacturer ’s specification . However , an ECM must be configure by the manufacturers so a car can do optimally , takingenginespecs and other factors into consideration . Even though OEM suppliers volunteer a diverseness of locomotive engine calculator products with different benefits and features , the same system can be tuned to work with a range of different auto . However , as a starting point , they ’re broken down into categories like fuel type ( gasoline or diesel ) , engine size and so on .
An ECM is a pretty basic railway car part – not to diminish its importance , but it ’s not the kind of feature that a car shopper would habituate to determine between different model . It ’s just there . An exception to this rule is modified cars that require to run a programmable ECM . We already mentioned MegaSquirt as one such example ( because it has the most memorable name ) – that system is designed specifically to operate usage fuel shot management . There are legion others with less colorful nickname that can help you if your custom engine direction needs are , for deterrent example , due to a really high - ending exhaust organization ( regulate oxygen and discharge ) or aftermarketturbochargers(to keep tabs on the engine ’s air inlet ) . Some of these take the place of the regular ECM , while others require to be constantly babied and nourish with additional accoutrements , like extra gauge or even extra computers . ( Remember Paul Walker racing in " The Fast and the Furious , " yelling at the laptop monitor his azotic injectors instead of really watching the street ? )
The good word is , unless you ’re doing research for a custom ECU or ECM for a specific purpose , like a weekend trail toy or a lead bike , you do n’t postulate to relate yourself too much with the differences amongst OEM railway locomotive computers . They ’re all designed to perform the same basic affair and you do n’t have a choice about what originally come in your car , anyway .
Regardless of the differences between dissimilar railway car model and different ECMs , the inputs in each organization remain fairly much the same . The ECM is tasked with providing fuel and regulating emissions , but there ’s a lot that needs to happen for that to work . We already talked about the ECM ’s specific task , but that simplify the process a bit too much . The ECM usually monitor and regulates the throttle position sensing element , which enjoin the engine how much atmosphere and fuel to mix to make power ; the coolant temperature detector , which let the locomotive engine get laid if it ’s running too hot ( and alerts the driver , via the instrument panel light ) ; the voltage governor , which tracks and adjusts how much baron is being direct throughout the car ; the fuel injectors , which provide fuel at precisely the correct moment for optimum power delivery ; the spatial relation sensors for the camshaft and crankshaft , which key out the engine ’s rhythm ; the mass flow of air sensor and MAP ( multiplex right-down pressure ) sensor , which monitor different ways tune affects the engine ; the oxygen sensing element , which measures exhaust quality ; unfounded ascendence ; the EGR valve sensor , which also help with emissions and the ignition control , which regulates the spark plugs .
And all of this is go on all at once , as the car moves – and reactions must be immediate . So it ’s a little nervus - wracking to think that the ECM can go bad just like any other car part . The consequences might be more dreadful than , say , the central processing unit on your laptop crapping out .
Engine Control Module Repairs
First off , do n’t confuse replacing an ECM with repair one . The closing result might be the same – you could drive your cable car again , after all – but engine ascendancy mental faculty and units do sometimes go speculative , and they are n’t really designed to be repaired – at least , not by the proprietor or by an average machinist . It should n’t be too hard to swap out a faulty ECM for a young one , but that ’s about as drug user - favorable as this summons can get . Quite simply , it take in specialized knowledge and specific cock to repair , not replace , an ECM .
Actually mend an ECM requires take apart the unit and perform some middling detailed , preciseness - critical electronics work . It ’s alike to repair themotherboardin a background computer – assuming it can be repaired it all . Some expert urge withdraw and opening the unit , and sniffing around for the telling sign of electrical hurt ( if you ’ve never smelled it before , weigh yourself lucky – but you ’ll probably still be capable to identify the chemical tang of sting metallic element ) . Also , if there is any corroding from acid or wet impairment , it ’ll probably be easily seeable . If you ’re not contrive to do the repairs yourself , the only benefit to this step is that you ’ll know you ’re on the right rails with your diagnosis . That sound out , the absence seizure of such evidence does not mean the ECM is fine . Got that ?
Your options are to grease one’s palms a unexampled ECM , or send in your old one and hold back for it to be repaired ( and you’re able to probably guess which one be less ) . So even if you or your mechanic suspects the ECM might be the source of your bother , you should trouble-shoot and annihilate all other potential problem before pulling the ECM and instal a new one . Replacement can be anywhere from several hundred to several thousand dollars , and can be made more complicated ( and expensive ) if the ECM has to be modified to accommodate surety systems , smart keys , immobilizers , or anything else electronic that is specifically configured to your railway car . And do n’t forget that many ECM fixing services are happy to rejoin a unit they determine is beyond repair ( if certain area of the central processing unit have been damage , critical data can not be retrieved ) . This might seem thwart at first – you might wonder what function a completely fry ECM could possibly serve – but remember that the unit store all kinds of personal datum from your car , which some multitude might not require left attend around forever in some random storage warehouse .
It ’s worth noting that , just as a bad ECM can make all variety of electrical problems , the inverse is also true – faulty or malfunctioning sensors can actually damage your ECM . That ’s another arguing in favor of follow a thorough troubleshooting routine before put on the generator of a problem . If you know you have a defective sensing element or two , get them replaced as soon as potential .
After researching this article , I ’m still not entirely exonerated on the deviation between an ECM ( engine command module ) and ECU ( engine control whole ) . Of the two terms , ECU seems to be the most popular . Google verifies its taste for ECU by delivering more elaborate search results , whereas some other reference seem to treat the ECM as a subcategory of ECUs .
In practical terms , I ’m not sure if it really matter . That ’s the finale I draw when reputable sources ( such as automotive repair manuals and long - show technology publication ) use the terms interchangeably . One of my pet authorization on explain automotive elaborateness to the average American , Mike Allen of Popular Mechanics , has , on social occasion , border the issue by referring to the organization as the " engine management computer . " One such reference was in an clause discourse the backlash against Toyota , when , in 2010 , a handful of its cars were come up to accelerate seemingly on their own – in other words , he was breaking down a complicated issue for people who were curious about it , but needed the state of affairs explained at the most canonical levels . ( Remember that ? A cluster of Toyota owner , exact their cars could accelerate on their own without admonition and all efforts to cease them flush it . The trouble was blamed on faulty machinelike accelerator controller units sending high-risk signals to faulty ECUs – or something like that – but never ultimately concluded . )
So if you found this clause by search for " locomotive engine control unit " or any other combination of interrelate terms , I desire this clear up up the confusion . And for what it ’s deserving , Mike Allen also managed to explain , in simple terms , why the ECU on a caboodle of Camrys , Corollas and Avalons merely could n’t have failed at the rate report by the media .
Related Articles
Sources
Engine Control Module FAQ
Please simulate / paste the next text to decently cite this HowStuffWorks.com article :
