Component Tests and General Diagnostics

When all tests and checks have been carried out in accordance with the diagnostics procedure for the relevant diagnostic trouble code, or by manual fault diagnosis, without any faults having been found, it is natural to assume that the control module is at fault.

Therefore, go through all the following points very carefully before definitely pinpointing the Motronic control module as the cause of the fault.

1. Check once again that every single point in the diagnostic procedure for the diagnostic trouble code in question has been carried out.

2. 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 electrical principles of operation at individual systems and wiring diagrams may be of assistance in this respect.

3. Check all grounding points. If you have already done so, do it once again. Check that power ground and sensors are physically and electrically separated from each other.

4. Check the control module's power supply.

5. Repair statistics show that the majority of all control modules returned for repair under warranty are in perfect working order. Be restrictive with control module replacement.

Unnecessary control module replacement represents a sizeable cost item for Saab Automobile and Saab dealers. Give careful thought to all possible causes of the fault before changing the control module.

When substituting a control module for testing purposes, always refit the original unit.

6. If the original fault still persists in spite of this, then the Motronic control module will have to be changed.