900 Turbo Convertible L4-1985cc 2.0L DOHC Turbo EFI (1994)
Engine Control Module: Testing and Inspection
Before Control Module Replacement
PROCEDURE BEFORE REPLACING ECM
When all the checks have been carried out in accordance with the diagnostic procedures program under the diagnostic 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.
1. Check once more that all the items for checking in the fault diagnosis routine for the relevant diagnostic trouble code have been carried out.
2. 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.
3. Check all grounding points. If you have done this previously, do it once more Check the the power ground and sensor are mechanically and
electrically separated.
4. Check the voltage supply to the ECM.
5. 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.
6. If the original fault nevertheless persists, the Trionic ECM must be replaced.
