Diagnosis By Symptom

NO COMMUNICATION WITH THE SRS (AIRBAG)





Fault Symptoms

Condition:
The following conditions are applicable:
- Ignition switch in ON position

Diagnostic Help:
First check the fuses for the Airbag control module and that no slide-out of the data link connector pins for communication with the Airbag has occurred. Then check whether the Airbag control module is awake and allows diagnostics communication. If this is the case, check whether the diagnostics tool works on another car.

If no fault can be found, repair or replace the communication lead between the Airbag control module and the data link connector.

Checking The Wiring Harness:
Jiggle the wiring harness at several points and in different directions to detect intermittent breaks and short-circuits in the leads. Observe the multimeter, test lamp or diagnostic tool during the test.

Diagnostic Procedure
1. Quick Check




- Check fuse 28 and change if necessary.




- Inspect pin 8 of the data link connector visually for possible pin slide-out.

Function OK?

YES
- Go to Point 2.

NO
- Rectify the fault.
- Go to Point 6.

2. Checking That The Airbag Control Module Is Awake.
- Turn the ignition switch to ON.

- The airbag lamp should come on for 3 seconds and then go out.





Function OK?

YES
- Go to point 3.

NO
- Go to point 4.

3. Checking The Diagnostic Tool

- Check whether the AIRBAG can be contacted on another Saab 9-3 using the same diagnostic tool.





Function OK?

YES
- Repair or replace the wiring between pin 8 of the data link connector and pin 12 of the airbag control module.
- Go to point 6.

NO
- Repair the diagnostic tool or change it, if necessary.
- Go to point 6.

4. Checking The Airbag Control Module's Current Supply and ground.




- Turn the ignition switch to OFF.




- Unplug the connector: Control module Airbag: (331)




- Connect a BOB (Break-Out Box).




- Turn the ignition switch to ON.

- Take a voltage reading.




- Read test lead: Control module Airbag: 5




- Black test lead: Good grounding point.

- The value should be B+.

Function OK?

YES
- Go to Point 5.

NO
- Repair or replace the relevant lead.
- Go to Point 6.

5. Checking The Airbag Control Module's Ground connection.

- Take a voltage reading.

- Red test lead: Control module Airbag: 5




- Black test lead: Control module Airbag: 7

- The value should be B+.

Function OK?

YES
- Go to Point 6.

NO
- Repair or replace the relevant lead.
- Go to point 6.

6. Final Check




- Clear the diagnostic trouble codes in all systems.

- Carry out a function test.

Function OK?

YES
- The steps taken to rectify the fault were correct.

NO
- See Control Module Testing and Inspection