Before changing an electronic control module
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Before changing an electronic control module
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When all checks have been carried out in accordance with the diagnostic
procedure described under each diagnostic trouble code heading without any fault having
been detected, it is natural to assume that the electronic control module is defective.
In view of the fact that the control module is an exceptionally high-quality component
and also extremely expensive, it is important to verify the diagnosis as far as possible.
Therefore, go through the following points very carefully before definitely pointing to the
control module or instrument as the cause of the fault.
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1.
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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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2.
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Study the wiring diagram of the circuit in question and make sure you understand
how it works. Relevant parts of the technical description and the descriptions of operation
explaining how components function electrically in Service Manual 3:2 "Wiring diagrams" may
be of assistance in this respect.
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3.
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Check all grounding points. If you have already done so, do it once again.
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4.
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Check the power supply and the fuses for the electronic control module.
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5.
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Be restrictive when it comes to changing control modules.
Unnecessary control module replacement represents a major cost to Saab Automobile
and Saab dealers. Give careful thought to all possible causes of a fault before changing the
control module.
When substituting a control module for testing purposes, always refit the correct plugs
in the control module's connector.
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6.
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If the original fault still persists in spite of this, a new control module will have to
be fitted.
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