Spurious Diagnostic Trouble Codes In the Airbag System (SRS)

Spurious Diagnostic Trouble Codes In The Airbag System (SRS)

Cars affected
Saab 9-5 4D M98-99 up to and including chassis number X3027793

Background
It may sometimes happen that the AIRBAG lamp comes on when no permanent fault is present in the airbag system. It has been found that this is often caused by poorly tightened terminals on the wiring harness between the control module and the seat connector. Diagnostic trouble code B2863 or B2868 will then be generated.

In the event of complaints from customers, proceed as follows.

Separate methods for LHD and RHD are described in this SI.

Parts required
51 07 842 Wiring harness (CA: 30581757)
79 71 880 Cable tie (3) (CA: 30509027)
79 84 784 Cable tie (2) (CA: 30551667)
30 04 785 Fabric-backed tape (CA: 30559782)

Tools
85 80 151 Kit, extraction tools, contact pins
86 12 335 Reference resistor

Diagnostic procedure, LHD

1. Remove the seats as described in WIS.
2. Remove the center console as described in WIS.
3. Fold back the carpets to expose the wiring harness and cable ducting. Open the covers on both sides of the cable ducts.
4. Unplug the connector from the control module.

5. Snip the cable tie at the cable outlet and separate the connector halves.
6. Extract the cable terminals in positions 10, 11, 13 and 14. Use a small screwdriver to press the locking tongue aside.

NOTE: The locking tongue may have to be pressed aside once again when the cable terminal is halfway out of the connector.

7. Cut off the cable terminals. Bend the ends of the cables back and tape them to the wiring harness.

8. Run the new wiring harness to the car's regular wiring harness. Orange cables to the left-hand seat and white cables to the right-hand seat.

IMPORTANT: Exercise care to avoid damaging the cable terminals when routing the cables.

9. Fit the cables in the connector.
Orange cables to positions 10 and 11.
White cables to positions 13 and 14.

10. Assemble the connector and fit a cable tie round the cable outlet.
11. Extract the cable terminals from positions 7 and 9 in the 29-pin connectors for each seat. Use special tool number 85 80 151.
Cut off the cable terminals. Bend the ends of the cables back and tape them to the wiring harness.

12. Fit the cable terminals in positions 7 and 9 in the appropriate connectors.
Orange cables to the left-hand seat and white cables to the right-hand seat.

13. Tape the new wiring harness to the existing one. Start at the 29-pin connectors on each side and wrap tape round them all the way down to the cable ducts.

To improve accessibility, the clip can be detached from the air duct (do not cut it off the wiring harness).

14. Fit the clip in place on the air duct.

WARNING: Make sure that the cables do not rest against any sharp edges.

15. Snip the cable ties securing the wiring harness at the handbrake lever.
16. Tape the new wiring harness to the existing one from the connector at the control module down to the cable ducts.
Fit a new cable tie.
Arrange any surplus length of cable in a loop inside the cable ducts.

17. Connect Tech 2.
18. Connect a reference resistor, part number 86 12 335, to the driver seat connector.
19. Switch on the ignition.
20. Clear diagnostic trouble codes in the SRS system.
21. Obtain readings of diagnostic trouble codes. A break in the passenger seat circuit should be indicated.
22. Switch off the ignition.
23. Transfer the reference resistor to the passenger seat.
24. Switch on the ignition.
25. Clear diagnostic trouble codes in the SRS system.
26. Obtain readings of diagnostic trouble codes. A break in the driver seat circuit should be indicated.
27. If other diagnostic trouble codes are generated, check that the wiring harness is correctly connected.
28. Refit the carpet. Fit the scuff plates and rear seat air vents.
29. Fit the center console as described in WIS.
30. Fit the seats as described in WIS.
31. Clear diagnostic trouble codes and use Tech 2 to check that the resistance in the SRS circuit is 2.5 ± 0.3 ohms in the circuit of each seat.
Disconnect Tech 2.

32. Start the engine and check that the AIRBAG lamp does not indicate a fault.

Diagnostic procedure, RHD

1. Remove the seats as described in WIS.
2. Remove the center console as described in WIS.
3. Fold back the carpets to expose the wiring harness and cable ducting. Open the covers on both sides of the cable ducts.
4. Unplug the connector from the control module.

8. Run the new wiring harness to the car's regular wiring harness. Orange cables to the left-hand seat and white cables to the right-hand seat.

IMPORTANT: Exercise care to avoid damaging the cable terminals when routing the cables.

9. Fit the cables in the connector.
White cables to positions 10 and 11.
Orange cables to positions 13 and 14.

10. Assemble the connector and fit a cable tie round the cable outlet.
11. Extract the cable terminals from positions 7 and 9 in the 29-pin connectors for each seat. Use special tool number 85 80 151.
Cut off the cable terminals. Bend the ends of the cables back and tape them to the wiring harness.

12. Fit the cable terminals in positions 7 and 9 in the appropriate connectors.
Orange cables to the left-hand seat and white cables to the right-hand seat.

13. Tape the new wiring harness to the existing one. Start at the 29-pin connectors on each side and wrap tape round them all the way down to the cable ducts.