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TECHNICAL REPAIR MANUAL

IN INJECTION MODULES

ELECTRONICS
2011
ECU REPAIR vol 1

Cassio Bittencourt

workshop support

http://www.suporteaoficina.com.br
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ecu repair two

DOCUMENT

PROTECTED

RESPECT COPYRIGHT

NO PART OF THIS MANUAL MAY BE

REPRODUCED WHATEVER THE MEANS
EMPLOYEES WITHOUT PERMISSION, BY
WRITTEN, BY THE AUTHOR.

SANCTIONS APPLY TO INFRINGERS

PROVIDED IN ARTICLES 102 TO 106 OF LAW 9.610 OF
FEBRUARY 19, 1998.
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Summary

Contents
Summary ................................................. ................................................................ ...................................... 3

Introduction................................................. ................................................................ ................................ 5

Currently, I hear a lot about repairing injection modules, but are all professionals who offer such services
capable of accurately diagnosing such
systems? ................................................................ ................................................................ ........... 5

1 .Constitution of the injection module........................................... ................................................ 5

the ecu ................................................ ................................................................ ................................................. 5

2.versions..................................................... ................................................................ ................................... 10

2.1 Old versions ..................................................... ................................................................ ..................... 10

2.3 New versions...................................................... ................................................................ ....................... 11

3.diagnoses..................................................... ................................................................ ............................. 12

3.1 Vehicle diagnostics ................................................... ................................................................ .......... 12

3.2 ECU diagnostics ................................................... ................................................................ ................ 13

. description and tests of the main components ..................................................... ................................... 15 4

4.1 Diodes and semiconductors ................................................... ................................................................ ...... 16

4.2 capacitors ................................................... ................................................................ .......................... 22

4.3 resistors ................................................... ................................................................ ............................. 27

4.4 Bipolar transistors ..................................................... ................................................................ ........... 31

4.5 Integrated circuits ................................................... ................................................................ ............. 44

5.Dedicated integrated circuits and processors ............................................... .......................... 57

5.1 The processor ..................................................... ................................................................ ................................ 58

5.2 Memories ................................................... ................................................................ ............................. 60

5.3 Busbars................................................... ................................................................ ................................. 62

5.3 The software..................................................... ................................................................ ................................. 64

5.4 Operating strategies ................................................... ................................................ 65

6 .Repairs and practical tests............................................ ................................................................ .......... 67

6.1 power supply test ............................................... ................................................................ 67

6.2 ECU ground test ............................................... ................................................................ .. 70

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6.3 Cold solders and bad contacts........................................................ ................................................................ ... 73

6.4 Matrix ................................................... ................................................................ ................................... 75

6.5 Damaged electrolytic capacitors........................................................ ................................................ 76

6.6 Throttle driver failure........................................................ ................................................................ 78

6.7 injector nozzle driver failure............................................................ ................................................... 81

6.8 Ignition coil drivers fault..................................................... ................................................. 83

6.9 Stepper motor driver failure ............................................... ................................................... 88

6.10 Relay activation driver failure ............................................... ................................................... 89

6.11 Faulty input circuits ............................................................ ................................................ 90

conclusion................................................. ................................................................ ................................... 91

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Introduction

Figure 1

Currently, I hear a lot about repairing injection modules, but are all
professionals who offer such services capable of accurately
diagnosing such systems?

Diagnostic errors are common in all professions, but errors due to

unpreparedness and technical incapacity are unacceptable.

embedded electronics, in order to improve knowledge

technician of mechanics and electricians.

1. Constitution of the injection

module
Figure 2
the ecu

The already known ecu or electronic control unit, is an electronic

control module, applied in several different functions, such as: engine
management, abs, airbag, automatic transmission
between others
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The ecu is very similar to a microcomputer, as it has processors,

memories, drives and converters like pcs, all mounted on a
printed circuit board that can have up to four layers with a copper
circuit (fig3). printed circuit, which is responsible for most of the
defects in

automotive ecus.

Figure 3

Returning to the composition of the ecu, it can be

divided basically into four blocks. are they:
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Figure 4

FIRST > power input and distribution better known as power source (fig4),
where the voltage will be reduced from 12vdc to 5vdc. in automotive ecus,
the working voltage is 5vdc, level used by almost all digital systems, but
some drivers in particular need a voltage greater than 5vdc

to operate.

We have in the figure:

A > input and protection diodes

B > capacitors

C > operational driver. This is a driver manufactured specifically for automotive

ECUs, as it performs the functions of
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source, where the voltage is reduced from 12vdc to 5vdc, control of relays,
link to communication line k.

Figure 5

SECOND > digital complex (fig5)

A > eeprom memory

B > main processor

C > safety processor (handles emergency injection parameters)

D > crystal

Where the processor and some peripherals treat the input signals coming
from the sensors, these signals are generally analog where an integrated circuit,
called an analog-to-digital converter, converts these analog signals into digital
ones, so that they can be processed by the processor, which operates only
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with digital signals. It is important to note that this converter

circuit can be incorporated into the processor.

Figure 6

The THIRD (fig6) is the block and is responsible for the input of
the sensors, where the preparation of the signals is carried out
so that they can be measured by the processor or analog-to-digital
converter.

In the fourth and last block, the output signal for the
actuators is composed of drivers (fig7). The drivers also
act as a converter, but in this case, converting the digital
signals into analogs, and also work as amplifiers directing
the actuators, the signals in the proper operating parameters.
the driver can be a simple transistor

Figure 7
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, usually power, or even a complex operational amplifier.

In this manual
we will only address
the injection module,
but serving as a basis for
the other modules.

Figure 8
2.versions
we can divide the ecus into two versions, the older versions
and, consequently, the more advanced ones.

we will start by approaching the oldest chronology

2.1 old versions

we will take as an example an ecu iaw 1g7 sd 10 (fig8)
manufactured by magneti marelli introduced in the brazilian
market in 1995. we can see in figure 8 the main electronic
components, as a particularity this ecu uses two processors.
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2.3 New versions

In this example (fig9) we have an ecu iaw 4afb.p1 magneti marelli
we can observe a much smaller number of components having as
special characteristics the processor and the drivers

The processor used in this ecu is the st10 168, a versatile

processor with many features, one of them is the size of its
internal memory, that is, it has a great storage power, used in this
model as main memory, a topic that we will address front.

The versatility of the drivers also helps to reduce components and

reduce the size of the printed circuit board.

Figure 9
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3.diagnoses
we will deal in this chapter, the subject that is perhaps the
most important in this segment,the
even
knowledge
more important
in repair.
than
we
will take as the first topic the diagnosis of the vehicle, which
verifies that the ecu is broken.

3.1 Vehicle diagnosis

Correctly diagnosing the real defect of the vehicle is
essential for anyone who wants to work with repairs in ecus, as
there are many errors between mechanics and electricians when
determining that the ecu is damaged.

It is of paramount importance for the professional repairer

in embedded electronics, to have test and simulation devices for
ecus, so that many ecus will be sent single, without the vehicle,
and if the first professional makes a mistake when diagnosing the
ecu, the second can test and verify that the damage is not in the
ecu but in the vehicle. Mistakes are common due to ignorance of
the particularities of the ecus, we must not forget that the ecus
has artificial intelligence, having operating and emergency
strategies, this emergency caused by external reasons the ecu,
which can confuse us with real defects. The ideal is that the
technician always has a MATRIX, that is, an ecu in perfect condition
for testing in the simulator or in the vehicle, to confirm where the
malfunction is.
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Once the ecu malfunction is found, the professional will go to the

second diagnosis, where the ecu malfunction is and the procedures
to be taken for the repair.

3.2 ECU diagnostics

Figure 10

with a careful visual inspection, we start our search for the defect,
many times, we visualize right from the beginning a burnt
component (fig10,11) or a copper trail
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broken.

Figure 11

If the ecu passes the visual test, we will proceed with the component
tests. the criterion for this test, and we follow and isolate with the help
of the injection electrical schematic, the block where the failure is,
example: if we have a failure in the injection nozzle ,we track the
electrical circuit of the same, inside the ecu until we reach the output
driver. and it is possible to find on the way, a broken track, a cold solder
or something that interrupts the circuit.if not, we will analyze the output
drive and components involved with the necessary tests.

We will continue with the example of injector nozzle failure, assuming

that there is a need to change the driver, after the change, the final test
is carried out, to which a satisfactory result is expected, otherwise, review
the work done from the beginning.
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4 . description and tests

of the main components
DATASHEETS

Datasheets are technical sheets with all the data of a

certain component. Most of the components found in ecus do
not have a datasheet, because some are dedicated, manufactured
specifically for that function, or have their nomenclature changed to
camouflage the component.

On this site we can safely search datasheets .http://

www.datasheetcatalog.com/

SMD COMPONENTS

In most automotive ECUs, surface mount technology (SMD, fig12) is a

method of building electronic components in which the components
(SMD, Surface Mounting Devices) are mounted directly onto the surface
of printed circuit boards (PCBs). Electronic devices with this technology
are called SMDS. An SMD component is generally smaller than its
conventional equivalent because the connections to its terminals

are smaller.
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Figure 12

In this MANUAL, we will discuss the conventional and smds

components, as we can find ecus with both types of
components.

4.1 Diodes and semiconductors

Most modern components, especially those considered active
(which amplify signals) are based on semiconductor technology.
Semiconductors are components based on the properties of silicon
and other tetravalent materials such as germanium, gallium, etc.,
capable of conducting current in a special way when they are doped
with certain impurities. Thus, there are basically two types of
semiconductor materials, depending on how they are doped. In P-
type silicon, for example, the presence of impurities such as iodine
causes a "gap" (fig13) or lack of electrons to appear, which gives it a
positive charge. In N-type materials, the impurity has a spare electron
and this gives it a negative charge (fig14).
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Figure 13

Figure 14

If we join two pieces of different materials, N-type and P-type,

(fig15) at the place where they are joined, the positive and
negative charges left over from these materials recombine forming
a semiconductor junction.
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Figure 15

This structure has a very interesting electrical behavior

that results in components called
solid state "diodes". These diodes differ from
vacuum diodes or diode valves, in the sense that current
flows in them through a solid material. If we polarize it in the
forward direction, (fig16) the loads recombine and the component
can carry the current without problems.

Figure 16
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However, if we polarize this structure in the opposite direction, the

junction region widens, forming a barrier that prevents the flow of
current. (fig17)

Figure 17

The components formed by this structure conduct current in

only one direction, which is a very important property in many
electronic applications. In figure 18 we have the most common
types of diodes with their symbol.

Figure 18

Diodes can be used to rectify currents (transform from

alternating to direct), in logic functions,
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as protective devices and in many other applications.

These components are specified by the maximum current they can
conduct (in amperes or milliamps) and also by the maximum voltage
they can withstand across their terminals when not conducting. There
are also diodes that have additional properties and are used in
applications
specific devices such as zener diodes.

ZENER DIODE

A very important diode for electronic applications is the zener diode.

This diode operates in reverse bias, as shown in figure 19.

Figure 19

DIODE TEST

Diodes must conduct current when biased in one direction and must
not conduct when biased in the reverse direction. It is based on this
behavior that we test the diodes, both with the multimeter on the
OHMS x10 or x100 resistance scale and with the continuity tester, as
shown in fig20.
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Figure 20

When we test it with the probes in one position, the diode

should have a low resistance. The LED should light up or else the
multimeter will show a resistance close to zero. When we invert the
probes the diode must present a very high resistance. The LED
should not light up or the multimeter should not have any changes
on the screen.

If in both tests we have continuity (low resistance) the diode is

shorted, and if in both tests the resistance is high, the diode will
be open.

SMD DIODE

We can test diodes in smd format in the same way as

conventional diodes, always observing their polarity, defined by
a dash (fig21).
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ecu repair 22

Figure 21

4.2 capacitors
Our next component is the capacitor(fig22)

We call passive components those that do not increase the

intensity of a current or voltage. The basic purpose of a capacitor
is to store electrical energy in small amounts.
However, in addition to this property, capacitors have others
that make them ideal for many circuit applications. A capacitor's
storage capacity or "capacitance" is measured in Farads (F). As
the Farad is a very large unit, it is preferred to use its submultiples:

Microfarad (µF) = 0.000 001 F

Nanofarad (nF) = 0.000 000 001 F

Picofarad (pF) = 0.000 000 000 001

See that 1000 nF corresponds to 1 µF.

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Figure 22

In figure 23 we have the aspects of the main types of capacitors

found in electronic projects

Figure 23

In addition to capacitance, capacitors also have another

specification, which is their working voltage in volts. if the
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working voltage is exceeded, a spark jumps between its armor

(internal parts) causing it to burn. Ceramic capacitors have an
identification code that the reader must know (fig24)

Figure 24

In low value types there is a capital letter that replaces the

comma and the capacitance is given in picofarads. For
example 4N7 or 4J7 indicates 4.7 pF. In higher value types,
the first two digits form the tens of capacitance and the third
the number of zeros, with the value given in picofarads. For
example 104 means 10 followed by 4 zeros or 100000 pF. Now,
100,000 pF is equivalent to 100 nF.

Also for capacitors we find the SMD types (for surface mounting
which are very small and have a similar shape to resistors.

CAPACITOR TEST

Capacitors cannot be tested very reliably with a multimeter or

continuity tester. The most that these devices can detect is
when there is a short circuit between their armatures. Thus,
capacitors must always present a very high resistance in the
proof of
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continuity(fig25)

Figure 25

For capacitors with high values (above 1 uF), when we

touch the probes to their terminals, the instrument's display
makes a small jump to return to the infinite resistance position.
This is normal, indicating that the capacitor charged during the
test.

However, if the display remains at constant zero, we have a

shorted capacitor.

SMD CAPACITORS
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Figure 26

In figure 26 we have an electrolytic capacitor in smd

format. We can test smd capacitors in the same way as the
conventional ones

We have to pay special attention to the ECU input smds

capacitors, (fig27) especially the sensor inputs, there are cases
in which these capacitors short circuit or decrease their resistance,
thus changing the input voltage of the sensor and its respective
value .in the figure we can see the sequence of input capacitors.

Figure 27
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4.3 resistors
Another group of important passive components found in
electronic circuits are resistors. Of all the passive components, the
most common are resistors appearing in large numbers in discrete
form in electronic equipment.

The purpose of a resistor is to present an electrical resistance

(measured in ÿ - O and its multiples such as kilohm and megohm)
in order to reduce a voltage or current in a circuit. The most
common types of resistors are carbon ones that have the shape
shown in figure 28, where we also show their symbol.
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Figure 28

The resistor values are given by the colored bands that follow
a universal code that every electronics practitioner should know.
This code is given in the table below (fig29) for
3 band resistors:
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Figure 29

Reading a resistor code works as follows for the 3-band type.

The first and second bands indicate the first two digits of the resistance
value. For example, yellow and violet: 47

The third band indicates the multiplication factor. For example,

orange x 1000.

So we have 47 x 1000 = 47 000 ÿ or 47 kiloÿ (47 k).

The fourth band, when it exists, indicates the tolerance. Silver

10% and gold 5%. The reading is always done from the edge to
the center, (fig24)

Resistors heat up when in operation. Therefore, their sizes are

determined by the dissipation capacity given in Watts (W). When
resistors work with very intense currents and therefore must
dissipate a lot of heat, they must be of special types. These are
nichrome wire resistors and similar types.

Like other electronic components, resistors can be connected in

series or in parallel.
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There are also resistors of very small sizes, called SMD

(Surface Mouting Devices or Components for Surface Mounting)
that are inserted in the circuits by machines and require special
equipment for removal and replacement.
We find these resistors in commercial equipment. These components
have their values indicated by special code.

RESISTOR TEST

Testing resistors with a multimeter is the most reliable, as we can

directly read the value of the component by choosing the appropriate
OHMS scale.(fig30)

Figure 30

SMD RESISTORS
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Surface Mounting Resistors (SM or Surface Mounting) of

SMD (Surface Mounting Devices) technology have a 3 or 4
digit code in their most common configuration, as shown in
Figure 31.

The tests for resistors in smd are the same as for

conventional, with the difference of not having to interpret the
color codes.

Figure 31

DIGITS 1=1 DIGITS 2=2 DIGITS 3=MULTIPLIER, THEN 12X100 = 1200 OHMS OR 1K2

DIGITAL 1=1 DIGITAL 2= POINT DIGITAL 3=6 THEN 1.6 OHMS

DIGITAL 1=POINT DIGITAL 2=2 DIGITAL 3=2 THEN 0.22 OHMS

4.4 bipolar transistors

Undoubtedly, the most important component of modern
electronics is the bipolar transistor. This active component can
generate signals, amplify signals and even function as an
electronic switch. The basis of operation of a good amount of
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electronic equipment is in the transistor. Bipolar transistors are formed by

structures in which three semiconductor regions of the N and P type are
arranged alternately. In figure 32 we show the two possible types of structures
with the
symbols of the transistors obtained.

Figure 32

Note that transistors have three terminals called emitter (E), collector (C), and
base (B). In the simplest form of using a transistor, the current between collector
and emitter is controlled by a current applied to the base. As a small base
current can cause a much larger collector current, we say that the transistor has
"gain", that is, it can amplify currents. Common transistors can have gains
between 5 and 800. This gain is also called the "Beta" or "hFE" of a transistor. In
figure 33 we have the typical way of using a transistor in an amplifier circuit, in a
configuration called "common emitter".
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Figure 33

Changes in a current applied to the signal input cause larger

current changes at the output. If the signal applied to the input is
obtained from a microphone, for example, corresponding to a
sound, at the output we get this amplified signal. We can connect
several steps like this in sequence so that each one amplify the
signal a little, in such a way that in the end, the signal appears very
amplified and can be applied to a loudspeaker.

This is how common amplifiers work. Of course, there are, in

addition to the components shown in this step, others, such as
capacitors and resistors that are used to transfer the signal from
one step to another or to prevent them from deforming (distorting).
Transistors for electronic applications are divided into three groups,
the appearance of which is shown in figure 34.

Figure 34
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General purpose transistors amplify signals of small

strengths and are normally small. RF transistors are transistors
that work with high frequency signals.
Finally we have the power transistors which are the largest and
usually have features for mounting on heat radiators.

Transistors are specified by the maximum voltage they

support between collector and emitter, their gain, the
maximum collector current and the maximum signal frequency
they can amplify (cutoff frequency).

FETS

FETs or Field Effect Transistors are special transistors that

have a working principle shown in figure 35.
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Figure 35

In these transistors the current flowing between the drain (d) and
source (s) electrets is controlled by a voltage applied to their gate
electrode, abbreviated as (g). Field effect transistors are
components capable of amplifying and generating signals, but
they are very delicate and can burn if not handled with care. The
very static charge stored in a person's body is enough to burn them.
In figure 36
we have a typical application circuit of this transistor. A control
signal causes current variations in the resistor connected to its
drain (d).
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Figure 36

A special type of field effect transistor is the Power MOSFET

or power MOSFET where "MOS" stands for Metal Oxide
Semiconductor" or metal oxide semiconductor.
These transistors can conduct very intense currents, on the
order of several amperes, and that is why they are used to
control high power loads such as lamps, motors, solenoids, etc.
They are widely used in ECUs. In figure 37 we have a typical
circuit with a transistor of this type, where we also show its
symbol.

Figure 37

Note that the arrow on the central electrode points inward, which
occurs in an "N" type transistor. In type "P" the arrow points out.
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DARLIGTOM

If we connect two transistors of the same type (PNP or NPN)

as indicated in figure 38, we can have a circuit in which the final
amplification will be the product of the amplifications of the
transistors used. For example, if we use two transistors with a
gain of 100, the circuit formed will have a gain of 100 x 100 = 10
000!

Figure 38

We can manufacture in the same housing two transistors

already connected in this way, so that we have a "super
transistor" or a "Darlington" transistor, as shown in Figure 39.
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Figure 39

Darlington transistors are very useful when high amplification is

desired, as the second transistor in the pair can be made to carry
strong currents. Thus, Power Darlingtons can control very strong
currents from weak signals. The external appearance of a
Darlington transistor is the same as an ordinary transistor.

We can only know that it is a Darlington by its number, by consulting

a manual. For example, TIP31 is a common transistor while TIP120
is a Darlington power transistor. The specifications of these
transistors are the same as for ordinary bipolar transistors.

OTHER SETTINGS FOR TRANSISTORS

In addition to the common emitter configuration, which is the most

used, transistors can also be used in common collector and
common base configurations. In figure 40 we have the common
base configuration compared to other components.
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Figure 40

In this configuration we have a voltage gain, which means that the

output voltage is higher than the input current and the input impedance
is very low. The output impedance is high.

For the common emitter configuration, the signal enters through the base
and is removed from the emitter, as shown in the circuit in figure 41.
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Figure 41

In this configuration we have a current gain, which means that

the output current is greater than the input current. The input
impedance is high and the output impedance is low.

In figure 42 we have the common collector configuration in which the signal

enters through the base and leaves through the emitter.

Figure 42

TRANSISTOR POLARIZATION

To polarize a transistor is to make the currents that it needs

to work flow through its terminals. This is done through resistors
and other components that bring the terminals to the voltages
necessary for the circulation of the desired currents. In a simple
form of bias, shown in Figure 43, we use two resistors at the base
and one at the collector.
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Figure 43

The base resistor fixes the current in this element while the
collector resistor determines both the collector current and the
voltage in this element. In this way, changes in the base current,
given by an external signal, are transferred to the collector in the
form of a greater change in current and an oscillation in voltage.
The gain, with some approximation, is given by the relationship
between the values of the two resistors used.

ESD

ESD stands for Electrostatic Discharge or Electrostatic Discharge.

This is the biggest problem that exists for the integrity of
electronic components. Bodies can acquire high electrical
charges for several reasons. In the case of our body, because we
wear shoes with insulating soles and walk on carpets and other
means, friction generates charges that reach more than 10,000
volts. This charge is accumulated in our body, without us realizing
it. If we touch the terminals of a component, discharge occurs and
the component burns.

We can feel this discharge in the form of a shock when we

touch an earthed body or a larger metallic body. This is what
happens when we touch a door lock or a faucet and get a small
shock. Resources to prevent charges from accumulating on people
are employed in workshops that work with sensitive electronic
components.
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TRANSISTOR TEST

The simplest test of transistors with the indicated

instruments is a "static" test that only checks the state of their
junctions.

It starts from the idea that the circuit equivalent to a

transistor is the one in figure 44 in which we have two diodes in opposition.

Figure 44

Note that this equivalence is structural and not functional,

which means that two diodes connected in the indicated way
do not work as a transistor.

So, what we do is check the continuity of the junctions of the

equivalent diodes in 6 measurements: 3 direct and 3 inverse, as
shown in figure 45.
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Figure 45

For measurements between base and emitter and between

base and collector, we must have a low resistance reading
(continuity) and a high resistance reading (no continuity). For the measure between
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collector and emitter, we must always have the high resistance

reading.

If we have a continuity reading where there should be no

then the transistor is shorted. If we have a no continuity (high resistance)
reading where it should be low, then we have an open transistor.

SMD TRANSISTORS

Figure 46

We will proceed in the tests of the smd transistors (fig46) in the same way of
the conventional transistors, increasing only the attention to its polarity, for
this the ideal is to have a technical sheet (datasheet) of the component.

4.5 Integrated circuits

Electronic circuits are formed by a set of electronic components such
as transistors, diodes, resistors, etc. linked in a certain way that depends on
what we want them to do. The idea of the integrated circuit is to manufacture in
a
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unique process, on a small silicon wafer these components

are already interconnected to perform a specific function as an
amplifier, a voltage regulator, an oscillator,
etc.

Thus, integrated circuits are different from each other in the

sense that each of them is made to perform a certain function.
This function is given by its number or identification. The result
of manufacturing the components on a chip is the integrated
circuit that can have the most diverse appearances, as shown in
Figure 47.

Figure 47

The type on the left in a metal casing is practically no longer

used. The types on the right can have many more binding terminals,
depending on their complexity. Some even have more than 250
connection terminals, which makes manual work with these
components very difficult. Integrated circuits with many small
terminals are intended for assembly by machines only.
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There are also the integrated circuits of complete

amplifiers that, because they work with intense currents, have
resources for mounting in heat radiators (fig48)

Figure 48

Integrated circuits are classified according to families,

according to the function they perform. The main ones are:

ANALOGS

Analog integrated circuits are those that work as amplifiers or

oscillators, generating signals, amplifying signals, etc. Then we
have audio amplifiers, oscillators, operational amplifiers, etc.

DIGITAL

The digital ones are those that work with only two levels of signals
(0 and 1) performing logical operations like the ones found
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on computers and ecus. There are two major families of digital

integrated circuits found in common practical applications. The TTL family
which is compatible with most computers and ECUs running at 5V voltage
and the CMOS family which works with voltages from 3 to 15V.

An important group of integrated circuits of this family is formed by

microprocessors. They are extremely complex integrated circuits that
can be programmed externally to perform a certain function. Some of
these integrated circuits have more than 10 million transistors inside. In
figure 49 we have a photo of a microprocessor

common.

Figure 49

The circuits of these components are not programmed in a specific way.

Through a program that the user must develop the transistors are
activated so that the component does what it wants. In this category we
also fit the microcontrollers, which are circuits that can
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be programmed to control external devices from keyboard commands or

sensor signals.

SPECIAL FUNCTIONS

There are several special functions available in the form of integrated

circuits. We can cite several examples:

PLL - The Phase Locked Loop are special integrated circuits capable of
recognizing a signal of a certain frequency. They are used as filters in
many applications.

VOLTAGE REGULATORS - These are integrated circuits that provide a

fixed voltage at their output regardless of the input voltage. We can
mention the 78XX series where the XX means the output voltage (06, 09,
12, 15 V...). These circuits are widely used in power supplies.

RECEIVERS - some integrated circuits have all the configuration to

assemble a radio receiver with few external components.

OSCILLATORS - are circuits specially designed to generate signals of

certain frequencies or even make timings.
The best known of this family is the 555 which generates signals up to
500 kHz. (*6).

EVOLUTION

Integrated circuits are evolving to contain more and more components.

Moore's Law states that every 18 months the number of components on
a chip doubles, and this has been happening practically since the
integrated circuit was invented. Today, in a single tablet it is already
possible to integrate more
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of 50 million components, and this happens with

microprocessors, such as those used in computers and ECUs.

For those who use these components, in most cases, specific

simple types that can be found in appropriate suppliers are
used in the projects, repairs and assemblies. Today there are
more than 1 million different types of integrated circuits that must
be identified by their type, engraved on the component itself.

In many cases, such as equipment for domestic and medical

use, etc., the code is given by the equipment manufacturer
himself, so the integrated circuit can only be obtained from an
authorized workshop, which makes repair work very difficult. In
other cases, however, common-use circuits are used, which can
be found at any hardware store. In this case, the replacement or
even the elaboration of a project is much simpler.

Examples of integrated circuits in this category are: 741,

CA741, LM339, TL072, LM7805, NE555, LM555, etc. Often, the
first two letters identify the manufacturer. For example, NE555,
LM555, TL555 are the same component but from different
manufacturers.

ECU INTEGRATED CIRCUITS

We can find common integrated circuits in automotive

ecus, such as voltage regulators, operational amplifiers,
comparators. But unfortunately we are not repairing a TV
or even a PC, because in most
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electronic devices we get your electrical schematic or technical

sheet, which does not happen with ecus.

Most of its integrated circuits are dedicated, manufactured

specifically for that function, and without repositories for sale,
making repairs very difficult.

Fortunately, in recent years, some of these components have

appeared on the market, making our work a little easier. A good
scrap is also essential for repair technicians, as we can use it
whenever necessary.

SMD ENCAPSULATIONS

Package types for integrated circuits in SMD technology can

be grouped into families.
The oldest technology is the “flat pack”.
The “Quad flat pack”, the TSOP and the BGA are the latest
technologically.
Each family has certain characteristics in common, such as terminal
type, terminal pitch, package size and materials (fig50).
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Figure 50

SOIC

The SOIC's (fig51) belong to the family of packages with the greatest
variety of terminals, both in terms of shape and number of terminals.
They are called by at least ten different names. There are slight
differences between them, and they are often called by the wrong
name. They are widely used in automotive ECUs, most often as memories.
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Figure 51

TSOP

The TSOP (fig52) combines a small height package (1.0 mm) with a pitch
between terminal centers of 0.5
mm
The TSOP provides a package that accommodates a large silicon wafer in
a high-density circuit.
There are 2 types of terminal arrangements for TSOP's.
Type I is the most popular TSOP package and its terminals are located at the
ends of the body.
The Type II has its terminals located on the side of the component body.

Figure 52

PLCC

The PLCC(fig53) is the most popular of the lead chip carriers. Its “J”
terminals always have a pitch of 1.27 mm. They are commonly available
with 18 to 100 terminals.
PLCC's are supplied in tubes or strung on spools.
As an alternative to the plastic body, leaded chip carriers are available in
ceramic, known as CLCC, and also in metal, known as MLCC.

PLCC's can be socket mounted or soldered directly to PCI's and are

easily replaced (repaired)
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in the field when socketed. For replacement of welded

components, some rework techniques are required.

PLCC's have been in use for over a decade and continue to be

a common item.

Figure 53

LCC

The LCC ceramic encapsulation (Fig54) is one of the

most resistant as it does not have terminals to damage. The LCC's
are soldered directly onto the printed circuit boards through their
soldering “islands”. Many of the LCC's have a lead pitch of 1.27
mm (50 mil) with gold-plated contacts that must be tinned before
surface mounting (welding).

LCC's are generally designed to meet military, aerospace,

telecommunication and high temperature applications.

Occasionally LCC's are called LCCC (Leadless Ceramic Chip

Carrier).

Figure 54
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FLAT PACK

The “flat pack” (fig55) is the oldest package of SMD integrated circuits.

They are available in 1.27 mm (50 mil) terminal pitch and feature 14, 16 or 28
terminals. In some cases where the package is larger, it has a configuration
with up to 80 pins.

“Flat packs” are only used in military, aerospace and other restricted
applications.

They present their straight terminals in their plastic packages and need
preforming before being used.
“Flat packs” usually have gold-plated terminals and require tinning prior to
assembly.
It should be noted that “flat packs” have their terminals on only two sides of their
body. See figure below:

Figure 55

QUAND FLAT PACKS

“Quad flat packs” (fig56) are known as “fine pitch” components, as long as
the lead pitch is below .65 mm (25 mil) to .3 mm (12 mil).

The “Quad flat pack” family is available in many options and is called by
different names.
Many developments are still underway with the
QFP encapsulation.
The “bumper pack” package is manufactured within the standard
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"
American JEDEC. The encapsulation built non-bumpered MFF” is
on the Japanese EIAJ metric standard.

Figure 56

BQFP

These protrusions on the edges of the components are called “bumpers”

and their main function is to protect the terminals during transport,
handling and assembly.
The “bumpered quad flat pack” (fig57) is manufactured within the
JEDEC standard in inch measurements. This means that 25 mil
steps are truly 25 mils (0.636 mm, not 0.65 mm).

BQFP's are built in plastic encapsulation, however they are also available
in a metallic body, known as BMQUAD.

Figure 57

TAPEPAK

TapePakÿ (fig58) was invented by National Semiconductor and is now

licensed for production by various manufacturers.
This component has its terminals stretched out in a plastic frame, without
the possibility of damaging them. It is possible for the component to be
tested while still on the frame, before cutting
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and preforming.
TapePakÿ is available with up to 304 terminals.
The main disadvantage with TapePakÿ is the preforming equipment,
which adds cost to the process.

Figure 58

BGA

It is the most modern technology in encapsulation(fig59).

Coplanarity problems do not exist, as the components have solder balls
instead of terminals.
Provide more connections than QFP's in packages
minors.

These components are also called SGA's, LGA's, OMPAC's and

PPAC's. All of them feature solder balls or columns and their bodies
are made of plastic or ceramic material.
The spheres are arranged in grids from 5 X 5 to 25 X 25, obtaining from
25 to 625 connections.
The silkscreen printing of solder paste does not require a critical step for
BGA's, nor does the remelting process.

BGA's have upper or lower concavities. The default pitches are 1.5
mm and 1.27 mm (50 mil).
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Figure 59

5. Dedicated integrated circuits

and processors
As mentioned before, there are several dedicated ci's in
ecus, as the driver L9113 (fig60) manufactured by the company st
semiconductors .on site
http://www.st.com/internet/automotive/home/home.jsp from st we can
appreciate several articles and datasheets of components used in ecus,
but not the datasheet of the L9113, which was manufactured by order of
magneti marelli, which did not release it.

Figure 60

this is a multi function ci because it executes relay connections,

processes the messages of the serial line k, and still is the source of
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system power .we can then notice the importance of such ci for
the ecu.

5.1 The processor

Like the ci's, there are also dedicated processors for automotive
ECUs, such processors strictly follow the technological evolution.
In the first models the ECUs were equipped with 8 BITS
processors, they evolved to 16 BITS and currently 32 BITS are
already used.

In figure 61 we can see an illustration of a processor

automotive divided into blocks.

Figure 61

PROCESSOR ARCHITECTURE
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This volume of bits that I mentioned is directly linked to the

physical size of the processor, because the more control lines
the processor has, the more bits it will work with.
Explaining better, the control lines are literally the processor
pins, an eight-bit processor will be able to command its
peripherals, connected only to eight control lines, already in a 32-bit
structure, with more command lines, more peripherals can be
controlled.
such peripherals can be drives, memories, or even another
processor, thus increasing the speed and power of
control .we can then say that an ECU equipped with a 32-bit
processor is four times faster and smarter than one that uses an 8-
bit processor.

We can observe the analogy of the size of the processor to its number
of bits

Remembering that the processor of fig 63, the st10f 280, of 32bits
has the PBGA encapsulation, where we could not observe
its 208 PINS.

Figure 63 32-bit processor Figure 62 8-bit processor

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5.2 memories
Other components of great importance in ECUs are the memories, where
engine operating data, confidential vehicle immobilizer information, mileage are

stored.

They can save data permanently or temporarily,

depending on their type.

RAM MEMORY

Random access memory, can be written and read, random because it can be
read in any direction, from beginning to end or vice versa. It needs electrical
energy to retain its data.
In automotive ECUs, RAM memory is used in

temporary storage of operating data, and each time the power is turned off, a
new readaptation must be carried out.

ROM MEMORY

Read-only memory, which is programmed by the manufacturer, without

rewriting capability, and used in ECUs as fixed operating calibrations.

EPROM

The eprons memories (fig64) are mainly read-only, but their data can be
erased by exposing their optical window to an ultra violet light lamp, and then
written with the aid of an eprons recorder. in ecus they are used to store
operating calibrations of the motor.
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Figure 64

FLASH

Undoubtedly, flash memory is the most versatile of memories, as it is a read

and write memory, it can be written and erased with electrical energy, it has
a large storage capacity, and does not depend on energy to maintain its data.
automotive ecus, usually in psop casing(fig65)

Figure 65

EEPROM
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They are read and write memories, like flashes, however, with less storage
power and reduced size.

In ecus they are used in most cases to store vehicle immobilizer data and
mileage. They are usually used in soic format(fig66)

Figure 66

EMBEDDED MEMORIES

In ecus and common we also see memories incorporated into processors, of

all types, but the most common are eeprons and flashes, in which they are
used as in the external form, but improving the project, as they are internal,
they save on connection circuits and size of

system.

5.3 Buses
We can define as bus the means of communication used by the processor
to communicate with its peripherals
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In the figure we can see an example of a bus used in pcs, which we

can use as a base for ecus

Figure 67

Buses are defined as follows:

LOCAL BUS: used by the processor to communicate with its main

peripherals, memories and auxiliary processors.

DATA BUS: line for sending and receiving data

how to send and receive data, and a bidirectional line.

CONTROL BUS: used to send commands and instructions.

communicates directly with drivers and auxiliary processors

ADDRESS BUS: destined for memory, sends and receives data

from a specific location in the system memory.

BARRIER IN AUTOMOTIVE ECUs

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The bus in ecus is the same used by any digital system. in

terms of repair, as it is a complex and very high speed
system, we don't have much to do, technically in ecus, the
resources we have to detect if the digital block is working , that
is, it is alive, and try to connect the scanner with the ecu, if we
can connect we are already sure that the digital block is in
operation. If not, we will see ahead in practical repairs as we should
proceed.

5.3 The software

Software can be defined as a sequence of instructions to be
followed and executed by a digital system. Also called a program,
in automotive ECUs, software and used in an embedded form, that
is, there is no operating system to manage its instructions, such as
on pcs. on embedded systems the programs are directed to
perform specific functions as in the case of ECUs, control of the
engine's operation.

The program used in automotive ECUs has a great power of

control and automation, because based on data from the
sensors, they are capable of precise calculations for later
formulation of commands for the actuators.

The operating strategies used in ECU programs are a huge source

of diagnostic errors by professionals, as they can be confused with
injection system malfunctions. We will give a brief description of
these strategies.
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5.4 Operating Strategies

The operating strategies are used by the ECU to achieve the
best possible operation of an injection system. and within these
strategies are the emergency modes. The emergency modes are
used whenever the system fails, so that the engine does not stop to
work, the ecu adopts a reference value, determined by the program,
for that fault or a different routine until the fault is resolved. in
emergency mode?

As we do not have access to precise information about

operating strategies, we have to pay attention on a daily basis,
testing and observing systems in operation and simulating failures
to know the behavior of operation with that induced failure, that is,
which parameter does the ECU assume with a certain fault.

EXAMPLE OF DIAGNOSTIC ERRORS CAUSED BY

OPERATIONAL STRATEGIES

A: in older vw vehicles, from 1997 to 2002, iaw 1avb and 1avp

systems, it is common to interrupt one or more wires from the
stepper motor, in the electrical wiring, as this vehicle does not have
a warning light, the technician will only know the failure to track the
injection. In this case, the ECU enters an emergency, cutting the
command signal to the stepper motor, remembering that in this case
the stepper motor has four wires, and the interruption or short circuit
of one of the wires , is enough for the ecu to go into emergency.
when working normally, with the help
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of a polarity pen, it is possible to visualize the command pulses coming

from the ecu. With the lack of these pulses in the case of interruption of
the wire, the ecu assumes a fixed value for all the other wires, being then
all grounded, which induces the professional to ''think'' that the ecu has
stuck.

B: in vw vehicles, Bosch MP 9 or iaw 1avs and 1avi vehicles, the

vehicle does not start for some reason, so the professional removes the
flute where the injectors are and notices that they all inject at the same time,
believing it to be a failure in the ecu and the possible reason for the vehicle
not working the same sends it for repair, not knowing that it is an ecu
strategy to keep the four injectors pulsing together until the vehicle starts
working.

C : almost all vehicles equipped with electronic throttle, when

with a failure in the throttle position potentiometer, the ECU adopts the
procedure of limiting or canceling the throttle command, leading the
professional to believe that it is the
ecu

CONCLUSION

We then concluded that we must be aware of the operating parameters,

especially the emergency ones, which can produce false failures in the ecu. I
remind you again that a good test and simulation platform is fundamental for
repairs in ecus, and also a stock of matrices, ecus in good condition for
comparison with a possibly broken one.
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6 .Repairs and practical tests

In this chapter, we will start the tests and repairs in
practice, starting with the system power phase.

6.1 power supply test

Figure 68

The first step for the power supply test (fig68) is to know if
the power supply is correct, with the help of the injection electrical
schematic and the multimeter we can trace the energy input in
the ecu, and verify if this voltage reaches the source, where will
be reduced from 12vdc to 5vdc. in most cases, we will find rectifier
diodes in the power supply circuit, after the diode, the voltage must
reach the 12vdc input of the source, if for some reason this voltage
is not active, check possible socket pins broken input chips, broken
copper tracks, burnt rectifier diodes. This test is also used to ground
the power supply.
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Once the power supply has been verified, we then proceed to the test of
the voltage regulator of the source, where one or
more circuits and blocks with the voltage of 5vdc. the better

procedure and isolate a known component, usually the system memories, in which
there is a datasheet released so that we can identify its power input and measure
if the 5vdc and grounds are present. (fig69)

Figure 69

after verifying the 5vdc and grounding, we concluded that everything is correct
with the source. If not, check for the possibility of a short circuit, which can be
caused by any component connected to this power line, starting a laborious,
but necessary search .the components most susceptible to short circuits are the
capacitors, especially the electrolytic ones(fig70)
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Figure 70

It will be necessary to disconnect from the circuit one by one,

because in a direct test it would always present a closed circuit,
if nothing is found in the capacitor test, we will go to the cis, which
like the capacitors we will have to disconnect from the circuit one
by one, removing the ci of the circuit, or simply, lifting its power
pins. the ideal is that when lifting the pin of the ci measure if the
pin that was raised, with its ground (fig71) therefore, in a possible
case of two or more components in short, the technician does not
get confused, if we analyze, he can lift the pin of a shorted ci,
measure the line that will continue to be shorted by another ci,
interpret that the ci that he tested is not the source of the short,
reconnect it to the circuit , and when in fact, isolate the other ci
that is also shorted, lifting its power pin, the line will continue
shorted by the first one that tested, and reconnected, closing the
circuit again. Pay close attention to this test.
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ecu repair 70

Figure 71

6.2 ECU ground test

Undoubtedly one of the simplest and most important tests for

the repairman, since 50% of the ECUs have ground faults,
causing all kinds of anomalies. battery reversed short circuit in
connections etc

We must first evaluate the grounding input on the ecu, at its

input socket, it is often not possible to see a broken pin at the
input of the board, under the insulators (fig72).
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ecu repair 71

Figure 72

We then proceed, identifying a known ci (fig73), and obtaining

its datasheet to find its grounding pin. and common cases of
grounding circuit breakage, in the internal tracks of the board,
then invisible to a visual inspection. It is also important to test all
other grounding points. All cis are grounded, and it is common for
a single ecu block to lose grounding, so grounding has to be
present in

all blocks.
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ecu repair 72

Figure 73

In figure 74 we can see a classic example of broken grounding.

Vehicle Kombi mp9 system, vehicle does not pick up and burn all
the coils that are installed, because without a path to drain, the
electric current finds the path of the ignition module.

Figure 74
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ecu repair 73

Likely cause a short in the wiring or poor installation of the battery,

which is just below the ECU support, favoring the contact of the
key used to tighten the positive pole of the battery, with the ECU
housing, breaking its grounding.

Most of the time, this breakout cannot be visualized,

having the technician with the described tests
previously encountered such a defect.

The solution found consists of a bridge, from the socket pin,

to an internal point of the circuit, which supports the grounding load.
We can see an example of this bridge in figure 75.

Figure 75

6.3 Cold solders and bad contacts

Many ECU memories are of the socketed type (fig76), and
susceptible to bad contacts, causing malfunction or
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ecu repair 74

none, just cleaning and refitting it correctly to remedy the defect. then before any

repair, check if the memory is socketed, if it is, do the described procedure

previously and test the ecu.

Figure 76

Cold solders are also great villains among the defects in ecus can cause from
malfunction to no functioning. initially proceed with a visual inspection, then go for
a test with a multimeter, if in doubt, test the firmness of the welded pin with a pointed
tool ( fig77).
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ecu repair 75

Figure 77

It is common to find components with loss of contact by cold soldering

in multec 700 and Le jetronic systems, caused by time of use.

6.4 Matrix
A great ally of the ecu technician is the matrix, an ecu in good
condition used in vehicle and simulator tests, but the matrix has
another important function, as its internal part is perfect, we can use
it as a reference for an ecu
defective, the repair of an ecu with a broken track in the internal
circuits of the board, it will only be possible if the technician knows
the path of that circuit, with the help of the matrix, the technician will
easily find the path, measuring with the multimeter, the beginning of
the circuit and its subsequent destination in
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matrix, then discovering the circuit to be made outside the board (bridge).

We can also measure with a multimeter, on the vcc scale, reference points and
compare with the defective ecu, in some cases we can with this test isolate the
defective block.

Figure 78

6.5 Damaged electrolytic

capacitors
The electrolytic capacitors (fig79) contain a liquid called electrolyte, highly
corrosive. With age, this liquid tends to leak from the capacitor, soaking the
printed circuit board, and consequently corroding it.

This corrosion interferes directly in the tracks of

copper, causing numerous malfunctions such as total system shutdown or

irregular engine operation.
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Figure 79

To solve the problem, the technician must remove

the capacitors, if necessary, redo the damaged tracks, clean with
isopropyl alcohol and replace the capacitors.

Electrolyte leakage may be noticed by the strong odor when

opening the ECU, but examination of the board surface after
removing the capacitor is indispensable.

Figure 80
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6.6 Throttle driver failure

One of the most common defects in ecus of more recent manufactures is
the loss of the electronic throttle command. in figure 81 we can see an
example of a dc motor control driver and its connections with the mcu
(PROCESSOR)

Figure 81

Caused by jamming of the gears of the TBI body, short circuit in the wiring,
inability to repair, where the mechanic forces the butterfly with the ignition or the
vehicle on and finally, time of use.

It is important to understand that when the ecu is controlling the throttle, it

has full control of its position, so any adverse force will damage the driver.

throttle motor control.

There are three most commonly used drivers in ECUs:

MOTOROLA MC33186DH DRIVER

We can easily get the datasheet of this component on the website

previously given. This driver is widely used in Bosch ecus

and magneti marelli.the shape of its housing allows for heat dissipation in the
printed circuit board itself.
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The diagnosis of this driver is simple, after a check on the TBI wiring and connectors,
just listen for the noise produced by the TBI, the absence of this noise configures a
defect in the ECU on the part of this driver (fig82).

To purchase the driver, visit the website

http://www.suporteaoficina.com.br

Figure 82

MOTOROLA DRIVER 16250829

We will find this driver in the Delphi ecus. unfortunately we will not be able to
obtain the datasheet for this ci (fig83).

Diagnostic procedures are the same as for the driver.

previous.
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Figure 83

To purchase this driver, visit the website : http://

www.suporteaoficina.com.br

DRIVER INFINEOM TLE6209

We found this drive in the ecus magneti marelli. It has similar

characteristics to the mc 33186 (fig84), as its metal housing serves as a heat
sink.

The datasheet of this ci is easily found and the

Diagnostic procedures are the same as above.

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ecu repair 81

Figure 84

To purchase this driver, visit the website : http://

www.suporteaoficina.com.br

6.7 injector nozzle driver

failure
There are many drivers used in the command

electroinjectors, as we did not get their datasheet, the best form of

diagnosis is the comparison of the circuit under test, with that of a matrix.

To identify the driver in question, we used the procedure of

tracking the electrical circuit with the help of the electrical schematic and
multimeter. We should also observe the integrity of possible components, which
have a direct connection with the circuit of the nozzles, most of the time the
capacitors.

In figure 85 we have an example of some drivers, they can be simple

transistors or even multifunction integrated circuits.
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Figure 85

We must pay attention to the wiring and installation of nozzle

simulators, used in CNG systems, as they are the biggest cause
of nozzle driver burnout.

Figure 86

It is common in ECUs that use transistors as nozzle drivers,

which can be tested as mentioned before.
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ecu repair 83

It is also common to have a failure in the activation resistor, which is

connected to the base of the transistor. Measuring with the multimeter
we can detect if everything is correct with the resistor (fig87).

Figure 87

To purchase this driver, visit the website :

http://www.suporteaoficina.com.br

6.8 Ignition coil drivers fault

Similar to the nozzle driver, the ignition coil drivers can range from
a simple transistor to a complex ci.

Test procedures are the same as for injector drivers.

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Figure 88

The activation resistors must be tested in the same way as the

nozzles. (FIG88)

Figure 89

In the case of figure 89 the ecu uses a carbon film resistor to drain
(ground) the electrical current coming from the coils.
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ecu repair 85

It is common in cases of short circuit of the coils, this resistor

breaks, opening the circuit. After the repair of the ecu, the coil must
be changed.

Figure 90

We can see in figure 90 the VB325SP ignition control drivers

frequently used in Fiat vehicles. We can easily find the datasheet of
this driver. We also see the activation resistors, which can be tested
as previously mentioned.

In the case of figure 91, we have a special case used in ecus

ford, a second driver in the circuit. this driver grounds the
transistor circuit.
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Figure 91

Figure 92

Unfortunately we do not have access to the datasheet of this ci,

which must be changed in all cases of ignition coil burnout.

In figure 93 we can see five transistors to control the coils, in

this case, an ecu from a Fiat marea vehicle.

This vehicle uses five ignition coils, and it is common to short

circuit the wiring or the coil itself, damaging the ecu. After an
eventual change of the transistor, the wiring must be repaired
or the ignition coil shorted.
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Figure 93

IGNITION CONTROL DRIVER L9134

This driver (fig94) can be found in ecus magneti marelli iaw 4sv
iaw 4bv, installed on vw vehicles.

It is common for it to burn by high voltage returns produced

by the coil, through the vehicle's electrical wiring. The most
common failure is the lack of pulse to activate the coil, cylinders 1
and 4. candle after your exchange.

Figure 94
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6.9 Engine driver failure

step

One of the biggest diagnostic mistakes in ecu is in the idling

phase. Mechanical and electrical defects in the injection lead
mechanics to wrongly “condemn” the ecu.

Cases of failure in idle control drives are rare, whether this

control is for solenoid valve or stepper motor.

For an accurate diagnosis, the ideal will be to use the matrix,

mentioned above. If the ecu has failed, the ideal is to start
tracing the circuit as has been said before.

In figure 95, we can see the U705 SDIC03 driver, widely used in
Sirius 32 ecu in Renault vehicles. In most cases this driver stops
working for time of use, but an inspection of the wiring, and tests
on the stepper motor coils and Always welcome.

Figure 95
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ecu repair 89

6.10 Relay activation driver failure

and common in ecus , faults in the relay command drivers, as they

are of great importance in the injection system, the fault is soon
noticed.

The most common faults are in the commands of the fuel pump relays and
cooling fans.

In figure 96 we will see the L9113 driver again, which is

responsible for activating the pump relays and electric fans
, and common in iaw49f iaw59f ecus, from Fiat, water infiltration
and subsequent accumulation at the bottom of the ecu, where
the L9134 driver is located. sometimes the electric fans circuit or
causing the driver to burn out.

As soon as the circuit damaged by corrosion is repaired, follow the ecu

test in the vehicle or in the simulator, without success, the next step is
to change the driver, change that should solve the problem once and
for all.
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Figure 96

6.11 Input circuit failure

Although most ecu failures are present in power circuits, the

input circuits also contribute to a large part of these defects. Shorted
capacitors, resistors with altered values, open or short circuit
transistors and even oxidized or broken copper tracks can

cause the ecu to malfunction.

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Figure 97

There are several reasons that can cause damage to components

or input circuits, the most common is humidity, often caused by poor
sealing of the ecu after a
reset or repair.

Component and continuity tests are paramount when faced with an ECU that
has a defective circuit.
input. as most input circuits are

analogue devices, it will not be difficult to diagnose them.

conclusion
We will then conclude this first phase of learning in basic and on-board
electronics. In this lesson we also understand that there is no "seven-headed
bug" in the ecu repair segment, and the commitment and attention of the
technician who are willing to this task is important. to the reader that to
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ecu repair 92

If you encounter a faulty ECU, carefully read the procedures

described in this manual.

We will discuss programming methods and means in the

next volume. For the purchase of components and technical
support, access http://www.suporteaoficina.com.br/

Thank you all .

Cassio Bittencourt

30 years old, electronics technician, works for 15 years in the

automotive area, during this period he took programming courses
in delphi, visual basic, microprocessors, digital serial ports. in the
, USB and electronics
city of Belo Horizonte, Minas Gerais, Brazil.