Before changing an electronic control module
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Before changing an electronic control module
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When all tests have been carried out according to the relevant diagnostic procedure without any faults having been found, it is natural to assume that the control module is at fault.
In view of the fact that the control module is an extremely high-quality component and also an expensive one, it is important to verify the diagnosis as far as possible.
Perform the following points
very carefully
before definitely deciding which control module/instrument caused the fault.
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Check once again that all points in the schedule for checking the operation of components, or all points in the diagnostic procedure for each diagnostic trouble code, have been carried out.
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Study the wiring diagram for the circuit in question and become familiar with its functions. If necessary, use applicable sections of the technical description and the electrical functions description in Service Manual 3:2 "Wiring diagrams" as an aid.
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Check all grounding points. If you have already done so, do it once again.
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Check the power supply and the fuses for the electronic control module.
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Be restrictive in regard to control module replacement. Unnecessary control module replacements constitute a major cost to Saab Automobile and Saab dealers.
Think of all possible causes of the fault before changing the control module.
After fitting a substitute control module for testing purposes, always refit the original control module.
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If the original fault persists in spite of this, the control module will have to be changed.
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