Repair of Automotive ECU and ECM without secrets! Download Free Manual’s

In today’s article I will talk a little about repairing electronic modules that equip cars, trucks, motorcycles and other vehicles existing since 1994. So sit in a comfortable place grab the coffee or a juice and get ready, because the reading will be interesting and extensive! 😉


Automakers have invested heavily in the deployment of first-world technology in their vehicles, and this will always be a strong trend, because who does not like the comfort and facilities that embedded electronics provides, is not it?

Download below the full handout with hundreds of tips!

Click here to download / Download



The complete course contains more than 300 pages, with tips on the most varied systems that equip the national vehicles, and their main flaws all cataloged enjoy! It’s free for you umgenio reader.

NOTE: The files are password protected, the password to unpack is:

Good Reading!

Diesel Power Plant Repair Course:

Free Diesel Central Repair Course Handout Download Here.
Also download the ECU’s Diesel Plant Repair Course Handout:

Update of files 01/02/2019: Added also the link to Download a handout with repair tips for Central / Ecu’s Of Heavy Vehicles – Diesel – Trucks and Trucks:

Click here to Download – Download


With the arrival of so many technology problems were solved, and cars became much more reliable and resourceful, previously nonexistent. A great example of advantage is the electronic injection and electronic management systems of otto and diesel cycle engines, which provide great fuel economy combined with an excellent use of engine strength.

However, with so much good also came some details …

That caused the automotive repair market to have to catch up and learn how to deal with today’s new car equipment.  Repairing cars is no longer simply just twisting screws and making mechanical adjustments. To get an idea still exist in Brazil, many autonomous repairers who still have difficulty solving problems in modern vehicles, and end up going through great frustration, besides leaving frustrated the customer. Unfortunately in Brazil, knowledge, tools and quality parts are still not 100% within reach of those who want to work.  Very different reality from other countries where it is more affordable and cheaper to learn how to work with automotive technology.

No more stalling, let’s cut to the chase!

Control modules and electronic equipment that equip vehicles usually present problems, and some besides expensive, are not found in the aftermarket, which makes feasible the repair of such modules. A modern vehicle currently manufactured can have several control modules in its bodywork, are they:

  • UCE Electronic Injection Module or known simply as ” Central “;
  • TCM Transmission Control Module or The Automatic Exchange Center;
  • BCM Bsi BC Body Control Module or Multi-Function Center that controls: headlights, courtesy lights, arrows, windscreen wiper, alarm, coded anti-theft key, electric windows with anti-crushing, electric locks, flashlights, defrosters and air conditioning;
  • Cooling Control Module: as its name says, it controls the operation of radiator fans to cool the engine;
  • Air Conditioner Control Module: controls air conditioning, both hot and cold;
  • Comfort Module: controls alarm, locks, electric locks, electric windows, sunroof, electrical seat settings, electric mirrors, accent heating functions, among other functions, depending on the vehicle model and its optional;
  • ABS Brake Control Module: this controls the operation of abs brakes, as well as controlling traction and stability control functions when available;
  • Airbag Control Module: this has the function of controlling the activation of airbag bags at the right time to reduce damage to crew members in case of accidents. This module also performs constant diagnosis of its sensors and actuators, and alerts the driver through warning light on the panel for possible malfunction of the Airbag system;
  • The speedometers of current cars are also considered modules.

These are just some of the modules that are found in modern vehicles, there are automakers who usually manufacture a separate module for each function of the car, making the systems more reliable, however, more complex.

All these modules, have logical data processing unit (processor), RAM and ROM, and are all interconnected through the CAN network.   Thus, everyone is managed by the main control unit of the car and it can make decisions to improve the operation of the vehicle, or perform real-time diagnostics, using the data crossing strategy.

The main frequent defects in plants and modules:

They are related to engine malfunction and transmission, in some cases may cause the vehicle to no longer enter operation or have its performance compromised. In the vast majority of cases, problems in plants are caused by external agents such as flood water, seawater, or even carelessness in the installation of a new battery (inversion of battery polarity, short circuit, or malfunction of the alternator). In other cases, the problems in modules are caused by wear of the car wiring, which causes short circuit, or by natural wear of actuators, which work in an unspecified regime and end up damaging the modules as well.

For example: An ignition coil with high voltage current leakage to the module harness or short circuit may cause the electronic injection module to burn, and thereby the vehicle may stop working. Another example is the malfunction of the idle actuator, if it is locked or short can also cause damage to the system.

IAW 4AF. M1, S2, M7, M9
Injection module components

In general, the plants of modern cars have the following internal configuration:

  1. Multi-Drivers: (Multi-function transistors, which control various actuators). This image controls nozzles, canister purge valve, cold start solenoid, injection relays, and idling actuator;
  2. Main Processor: (MCU type with built-in ROM and RAM) programmable via K line;
  3.  CI Voltage regulator 5 volts: feeds all module circuits and external sensors using 5 volts;
  4.  Mosfet transistors;
  5.  Drivers for Ignition Coil Control: control the spark of the coils;
  6.  Electrolytic Capacitor: Filters the power voltage to the 5 volt regulator;
  7.  Crystal Oscillator;
  8.  Rectifier Diodes;
  9.  EEPROM memory: containing immobilizer data and chassis number, accessory configuration;
  10.  ” * ” Communication circuit with the Can Network;


Electronic injection modules can be faulted for a variety of reasons;

  • Intervention by untrained persons or technicians;
  • Logical programming failure or corrupted memory;
  • Failures caused by water infiltrations in the body work or floods;
  • Failures caused by rays (cases are rare);
  • Failure caused by premature wear of components (manufacturing defect);
  • Failures caused by natural wear and tear of the car’s electrical installations, components external to the module;

Intervention by person or untrained repairing technician/mechanic is the most common cause for failures in embedded electronics systems. Unfortunately in the country where we live it is still difficult to acquire technical knowledge about new technologies embedded in automobiles, and many repairers end up learning to work hard, and failures due to lack of knowledge become common, but unintentional.  Simply installing an accessory in the vehicle such as an alarm or anti-theft, cutting power or stereo, if not done correctly can affect the car’s electronic systems, causing adverse effects and unwanted failures.  Often the owners themselves want to venture to move in their own car and end up by accident causing failures of the kind.

Examples of failures caused by humans, (laughs) :

  • Wrong installation of: accessory, xenon lights, sound, electric glasses, and DVD amplifiers;
  • Installation of: candles, coils, ignition cables of poor quality or unspecified;
  • Inversion of battery polarity or polarity inversion when taking a ‘jump’ on the battery;
  • Inversion of wires of sensors or actuators of electronic injection;
  • Installation of adapted parts not specified to the vehicle;
  • Electric gambiarras in general: be wary of everything or take the subsequent damage;

Programming failures and corrupted memory are very common in modules that work with MCU (a type of processor, which has ROM, RAM, and EEPROM memory, all integrated into a single chip). And they can be easily corrected, with the help of a copy of the files of a module in good condition and a compatible programmer for the rewriting of the data on the chip.

See this article that shows how to recover an ECU with corrupted memory.

Failures caused by water infiltrations in the body work and immersion of the vehicle in floods are also a very common cause of failure of automotive electronic systems, and this in turn is one of the most catastrophic, because in some cases it can mean total loss of the vehicle (even imported luxury vehicles, may have total loss depending on the amount of damaged modules).  In terms of ease of repair, a completely oxidized module, also something very difficult to repair successfully, because with the amount of components and micro sensitive tracks, corrosion is very large and in most cases, the module does not work normally again.

Failures caused by… Water?!

  • Washing sensitive parts of the vehicle or cabin may cause damage;
  • Water infiltrations in glass rubbers, gutters, that tassel of the breezes;
  • Floods, unfortunately our beloved cars are not waterproof, and can suffer failures when falling into rivers, lakes and floods;

Failures caused by lightning and natural electrical discharges are less common but are still a known cause for failure in embedded electronics systems in automobiles, especially when the vehicle is struck by lightning, whether in operation or stopped, parked.

  • If your car got close to the crash area of lightning, and after that it didn’t work anymore, then you may have been awarded…  Not that the prize is good, but that’s it, maybe the modules burned down.
  • When making a weld in the bodywork of the car remove the electronic modules outside to prevent burning.

Failure caused by premature wear of the internal components of the module, has its share of cause of failures that leave the repairman confused, not knowing for sure how to proceed to perform the repair of the vehicle. An automaker in Brazil a few years ago (around 2008, 2010) faced recurring problems in several models that shared similar electronic systems, failures were cataloged and affected vehicles suffered silent recall.  Even so, there are still units running that have not yet presented problems, and at one time or another will fail and leave their owners in hand without warning.

  • I’m not going to speak on behalf of an automaker so i don’t get in trouble with anybody, but that’s a reality, you have to admit!  In my day to day I see a lot of this in vehicles that are newly launched and debut some technology.  The first units always come with some hidden.

Failures caused by natural wear and tear of the car’s electrical installations and components external to electronic modules are also quite common and basically the most frequent failures are related to peeled wires, poor grounding, alternator defect, battery charge regulator system.

  • This is undoubtedly a villain that causes fear, because if not successfully diagnosed can re-burn modules or damage them over time.
  • Normally, vehicles with very deteriorated electrical installation need special attention to solve the problem, and the most indicated is the making of a new whip.

Failures in the immobilizer system (Coded Key) :

In general, failures in immobilizer systems happen with older vehicles and can also leave the engine inoperative. In many cases it is possible to generate a new key or exchange some component of the system and the system will return to normal operation.

But, there are cases where nothing seems to solve the problem, so a solution that works for many vehicles (new and old), basically consists of disabling the encoded key, and the vehicle can work without the need to chip in the key. This method is known outside brazil as “immo off”, or basically disable immobilizer.

Usually, to disable the immobilizer and eliminate the need for encoded keys just program the electronic injection module for this, with the help of a compatible memory programmer and with the correct set of files, you can disable and make the car fault-free with this system.

Here’s a full article teaching you how to repair or disable the immobilizer.

Automotive Immobilizer Repair, Reset and Decode, how to do:

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