Procedure before replacing ECM
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Procedure before replacing ECM
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When all the checks have been carried out in accordance with the diagnostic
procedures programme under the diagnostid trouble code concerned or through manual fault
diagnosis without any fault having been detected, it is natural to assume that the ECM is
faulty.
You should therefore run through the following points carefully before finally identifying
the Trionic ECM as the cause of the fault.
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1.
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Check once more that all the
items for checking in the fault diagnosis routine for the relevant diagnostic trouble code have
been carried out.
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2.
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Study the wiring diagram of the relevant circuit and examine its operation. If
necessary, consult the relevant parts of the technical description and the description of
electrical operation in Service Manual "3:2 Wiring diagrams".
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3.
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Check all grounding points. If you have done this previously, do it once
more. Check the power ground and sensor are mechanically and electrically
separated.
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4.
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Check the voltage supply to the ECM.
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5.
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Experience from the 1993 model shows that 80 %% of all Trionic ECMs returned
for repair under warranty were OK. Do not replace the ECM unnecessarily. ECMs replaced
without reason represent a large cost item for Saab Automobile and its dealers. Think through
likely causes for the fault before replacing the ECM. When replacing for test purposes, always
refit the correct ECM.
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6.
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If the origional fault nevertheless persists, the Trionic ECM must be replaced.
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