SIR Telltale Lamp ON with DTC 24 in SDM Memory

The SIR telltale lamp may be ON with diagnostic trouble code (DTC) 24 stored in the sensing and diagnostic module's (SDM)s memory. On 1996-1997 vehicles, if a DTC 24 is set, DTC71 will also be present, which requires the SDM to be replaced.

The wire leads from the SIR coil assembly to the inflator module may have shorted to ground on the lower left steering wheel puller hole.

Follow the procedure in this bulletin to identify and repair the condition.

Service Precautions.

Caution: When you are performing service on or near the SIR components or the SIR wiring, you must disable the SIR System. Use the following procedure to temporarily disable the sir system. Failure to follow the correct procedure could cause Air Bag deployment, personal injury, or unnecessary Sir System repairs.

1. Perform the SIR Diagnostic system Check. Refer to the appropriate year SIR Service Manual.

•	If DTC 24 is active, refer to diagnostic procedure in the appropriate year SIR Service Manual.

Important: If the driver inflator module is removed during the diagnostic or repair of DTC 24, install insulator as instructed in step 42 of this bulletin before reinstalling the driver inflator module.

•	If DTC 24 is in history only, follow the procedure in this bulletin to inspect and repair SIR coil assembly and install the insulator.

2. Turn the steering wheel so that the vehicles wheels are pointing straight ahead.
3. Turn the ignition to the LOCK position and remove the key.
4. Remove the AIR BAG fuse from the I/P junction block.

Important: With the AIR BAG fuse removed and the ignition switch ON the AIR BAG warning lamp will be ON. This is normal operation and does not indicate an SIR system malfunction.

5. Remove the connector position assurance (CPA) device and disconnect the yellow 2-way connector located near the base of the steering column.



6. Remove the upper trim panel screw caps by carefully prying with a flat-head screwdriver.
7. Remove the upper trim panel screws.



8. Lift the upper trim panel at the clip locations on the rear edge to disengage the clips.
9. Pull the panel rearward out of the clips at the bottom of the windshield.

Important: Be careful, when removing or replacing the upper trim panel, not to damage VIN plate.

10. Remove the upper trim panel.



11. Remove the upper trim panel insulator.



12. Remove the connector position assurance (CPA) device and disconnect the yellow 2-way connector located on the pigtail from the passenger inflator module.




Caution: When carrying a live inflator module (Air Bag), Make sure the bag and trim cover are pointed away from you. Never carry an inflator module (Air Bag) by the wires or connector on the underside of the module. In case of an accidental deployment, the bag will deploy with minimal chance of injury. When placing a live inflator module (Air Bag) on a bench or other surface, always face the bag and trim cover up, away from the surface.

13. Remove the screw caps on the steering wheel by carefully prying with a small flat-head screwdriver.
14. Remove the inflator module screws.
15. Lift the inflator module out of the steering wheel.



16. Remove the connector lock device with a small flat-head screwdriver. Disconnect the connector and remove the inflator module.



17. Inspect the wires leading from the SIR coil assembly to the driver inflator module.

•	If there is damage to the wires, proceed to the next step and replace the SIR coil assembly.

•	If there is no damage to the wires, proceed to step 42.

Notice: Always align the front wheels to the straight ahead position when installing or removing an SIR coil assembly.

Important: It is not necessary to install the driver inflator module until directed to do so while performing DTC 24 diagnostics in the SIR Service Manual.

18. Position the vehicle with the front wheels pointed straight ahead and the steering wheel centered in the straight ahead position.



19. Disconnect the cruise control switch (if equipped) and horn switch connector.
20. Remove and discard the steering wheel attachment nut .
21. Install the steering wheel puller onto the steering wheel and remove the steering wheel.
22. Feed the wiring through the steering wheel and remove the steering wheel.



23. Remove the screws and upper steering column shroud.
24. Rotate the key to the ACC position, depress the lock button and remove the ignition key.
25. Remove the screws and lower steering column cover.
26. Remove the SIR coil assembly rosebud-type fastener from the bracket below the steering column.
27. Disconnect the horn/cruise in-line connector, located under the steering column.
28. Remove the screws from the SIR coil assembly.
29. Remove the SIR coil assembly pigtail from behind the lever control switch.
30. Remove the SIR coil assembly.

Notice: A new SIR coil assembly is equipped with a yellow tab that is removed after the steering wheel is installed on the steering column. This yellow tab passes through the steering wheel at the pass through hole.

31. Route the long pigtail of the new SIR coil assembly and horn/cruise in-line connector behind lever combination switch and down the steering column.
32. Install the SIR coil assembly to lever combination switch.
33. Install the lower steering column shroud.
34. Install the ignition lock cylinder assembly.
35. Install the upper steering column shroud.
36. Route the wiring through the steering wheel.
37. Install the steering wheel onto the steering shaft noting the orientation notch that locates the steering wheel in the correct position.
38. Remove the yellow tab from the SIR coil assembly.

Important: Always replace the steering wheel attachment nut with a new nut. Never reuse the old steering wheel attachment nut.

39. Install a new steering wheel attachment nut.

Tighten
Tighten the nut to 40 N·m (30 lb ft).

40. Connect the cruise control connector and install the cruise control switch (if equipped).
41. Connect the horn/cruise in-line connector, located under the steering column.



42. Install a hood insulator retainer P/N 21039146 into the lower left steering wheel puller threaded hole to isolate the wiring harness from any sharp edges. This retainer is released as a hood insulator retainer for 1991-1994 model year vehicles. However , it can be used in this hole to prevent any possibility of wire chafing due to sharp edges.
43. Connect the inflator module to the wiring harness and install the integral connector lock device.
44. Install the inflator module into the steering wheel and tighten the fasteners, being careful not to cross thread the fasteners.

Tighten
Tighten the fasteners to 10 N·m (89 lb in).

45. Snap on the screw covers

Important: On 1996 and 1997 vehicles if a DTC 24 is set, a DTC 71 will also be present. Since DTC 71 cannot be cleared from SDM history, the SDM must be replaced.

46. On 1996 and 1997 vehicles, replace the sensing and diagnostic module (SDM). Refer to SDM Replacement procedure in the appropriate year SIR Service Manual.



47. Connect the yellow 2-way SIR connector at the base of the steering column and install the connector position assurance (CPA) device to the connector.



48. Connect the yellow 2-way passenger inflator module pigtail and install the connector position assurance (CPA) device to the connector.




Important: 

•	Make sure to tuck in all flaps.

•	Be sure the upper trim panel seal is correctly seated on the forward edge before installing the upper trim panel.

49. Install the upper trim panel insulator.



50. Install the upper trim panel into the clips at the base of the windshield.

Important: Be careful, when removing or replacing the upper trim panel, not to damage the VIN plate.

51. Lower the panel, making sure the upper trim panel alignment tabs interlock with the windshield garnish slots.
52. Push down at the clip locations to secure.



53. Install and tighten the screws.

Tighten
Tighten the screws to 2.3 N·m (20 lb in).

54. Install the screw caps.
55. Install the AIR BAG fuse to the I/P junction block.
56. Turn the ignition switch to the RUN position and verify that the AIR BAG telltale lamp flashes 7 times and then turns OFF. If it does not operate as described, perform the SIR Diagnostic System Check.