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Fault diagnosis strategy for electronic systems

Fault diagnosis strategy for electronic systems



1. The fault diagnosis strategy adopted should be based on the customer's description of the trouble.

If necessary, the customer must demonstrate the trouble on the car to avoid all misunderstanding.

2. In some cases, everything might be in proper working order.

2.a. Good product knowledge is required in order to determine this.

2.b. If everything is in proper working order, this must be explained to the customer.

3. If the trouble is due to a defect, the car must be repaired.

Saab's fault diagnosis strategy is based on the technician or mechanic knowing the customer's description of the trouble. Therefore make a note of the customer's complaint and any other pertinent observations on the job card.

4. The technician obtains readouts of diagnostic trouble codes from all systems.

A malfunction in one system could easily be caused by a fault in another system.

5. Diagnostic trouble codes which refer to secondary faults may have been generated in the car or the codes may have been generated erroneously.

5.a. Compare the customer's complaint with the description of symptoms for the different diagnostic trouble codes. EPSI has a rapid search path for this.

5.b. If the description of symptoms for any diagnostic trouble code coincides with the customer's complaint, this trouble code is probably caused by the primary fault.

Repair the car as indicated.

6. If there are no points of coincidence with diagnostic trouble codes, fault diagnosis can be carried out on the basis of symptoms.

6.a. Search in EPSI under fault diagnosis on the basis of symptoms in the system where the fault occurs.

6.b. If the description of symptoms in the system concerned coincides with the customer's complaint, the right fault diagnosis description has probably been found.

Repair the car as indicated.

7. If there are no points of coincidence with diagnostic trouble codes or symptoms, the technician or mechanic will have to carry out fault diagnosis unaided.

Final inspection and testing must be carried out after the car has been repaired.

Good technical product knowledge is required in order to solve this type of problem.

8. The car is ready for collection by the customer.