Trouble Godes - diagramas.diagram...

Tools & equipment
The method of fault code output varies considerably from manufacturer to manufacturer. The simplest to access are flash
type codes displayed with the malfunction indicator lamp (MIL) on the instrument panel Fig. 1 - or an LED display on the
control module Fig. 2 - these do not require any special equipment.
Systems requiri~pecial tools or equipment may output fault memory data as numerical codes or as plain text
messages.
Many different types of diagnostic equipment are available for reading self-diagnosis fault memories.
These vary from simple LED based testers, for reading flash type codes, to software based scan tools fully compatible
with EOBD requirements and incorporating many additional features, including the facility to be connected to a PC and
printer.
Some flash type codes are very complex, with up to ten flashes per group and four or five groups of digits, so that reading
them accurately with an LED tester is difficult and the possibility of miscounting is quite likely.
Some code readers can only display numerical codes, which means that they are unsuitable for use on certain makes and
models (such as Renault, Rover, Fiat etc.). These require equipment capable of displaying fault descriptions in plain text.
Most scanner tools will enable fault codes to be erased without disconnecting the battery, therefore avoiding the loss of
radio codes and control module learnt values.
Any software based equipment will need to be updated periodically by replacement 'pods' or CDs provided by the
equipment manufacturers.
Additional features accessible with the more sophisticated testers include:
Activation and functional testing of specific actuators and sensors.
a Multi-meter ranges.
Recording and displaying oscilloscope patterns.
n Links to menu based fault diagnosis procedures, with wiring diagrams, technical data and fault finding flow charts.
Fig. 1
Instrument panel malfunction
indicator lamp (MIL)
General recommendations
Fig. 2
- \
Control module with LED indicator
Electronic control modules such as the engine control module (ECM), transmission control module (TCM) and immobilizer
control module need special care during fault diagnosis. They are easily damaged by excess voltage or reversed polarity.
Whenever possible disconnect them before testing wiring continuity.
Some ECMs have an adaptive memory which may have to re-learn its basic dynamic values (during driving) if the power
supply is interrupted, for instance to erase fault codes.
Electrical wiring can be repaired where practicable but ensure that all repairs are properly insulated, preferably with heat
shrink tubing and protected by a fuse of the correct amperage.
NOTE: Many electronic control modules have fault memories which may be erased if the power supply is interrupted.
Check condition of ALL fuses in the system prior to circuit testing.
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