Intermittent/Flashing Air Bag Light, DTC U1088 (Replace Sensing and Diagnostic Module)

Some customers may comment on an intermittent and/or flashing air bag indicator lamp. Further investigation may find that DTC U1088 has been set.

During normal vehicle operation, the Sensing and Diagnostic Module (SDM) is in communication with the Instrument Panel Cluster (IPC). However, as a result of some software programming in the SDM, this communication may be interrupted intermittently. If this condition occurs, the IPC will see momentary losses of communication with the SDM and will set a Diagnostic Trouble Code (DTC) and will turn the indicator light "ON" and "OFF". These momentary losses of communication last for less than a second. During these intermittent losses of communication, the SDM continues to perform all other functions properly.

Replace the Sensing and Diagnostic Module (SDM) and reprogram the Body Control Module to accept the new SDM part number using the following service procedure.

Important: This bulletin does not apply to those vehicles listed in GM Product Safety Campaign #00073, issued September, 2000.

Service Procedure

Important: For additional information, see the SIR sub-section in Restraints and the Seats sub-section of Body and Accessories in the appropriate Service Manual.

1. Disable the SIR System.

1.1.	Turn the ignition to the OFF position and remove the key. [OFF to LOCK -- key can be removed only in the lock position].

1.2.	Remove the driver's side instrument panel access cover and remove the SDM fuse.

1.3.	Remove the passenger side instrument panel access cover and unclip the frontal air bags yellow 4-way connector from the metal rail, remove the Connector Position Assurance (CPA) and disconnect the frontal air bags connector.

1.4.	Remove the left side instrument panel access (insulator) cover, remove the CPA and disconnect the yellow 2-way steering wheel air bag module connector near the base of the steering column.

1.5.	If the vehicle is equipped with a side air bag, remove the CPA from the driver side air bag yellow 2-way connector located under the driver's seat and disconnect the connector.

2. Remove the passenger seat track adjuster front covers.
3. Move the passenger seat forward so that it is between the full forward and halfway position. Also, if equipped, move the seat to the full-up position.
4. Remove the seat belt fastener from the front seat track.
5. Remove the seat track adjuster to floor pan rear bolts.
6. Disconnect the seat electrical connectors.
7. Tip the seat forward and disengage the front seat track hook attachments from the floor pan.
8. Remove the passenger seat from the vehicle.
9. Remove the right front carpet retainer and reposition the carpet to access the SDM.
10. Remove the CPA from the two SDM electrical connectors and disconnect the SDM connectors.
11. Remove the SDM mounting bolts and remove the SDM.
12. Install the new SDM and mounting bolts.

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

13. Connect the two SDM electrical connectors and install the CPA's.
14. Reposition the carpet and install the right front carpet retainer.
15. Install the passenger seat in the vehicle and engage the front seat track hooks in the floor pan openings.
16. Connect the seat electrical connectors.
17. Install the seat track adjuster to floor pan rear bolts.

Tighten
Tighten the bolts to 42 N·m (31 lb ft).

18. Install the seat belt to front seat track fastener.

Tighten
Tighten the fasteners to 42 N·m (31 lb ft).

19. Install the passenger seat track adjuster front covers.

Important: When enabling the SIR system in the next step, do not turn the ignition switch to the ON position to verify proper operation. Verification of proper operation should only be done after completion of the entire procedure.

20. Enable the SIR system.

20.1.

If the vehicle is equipped with a side impact air bag, connect the driver side air bag yellow 2-way connector located under the driver's seat and install the CPA.

20.2.

Connect the steering wheel air bag module yellow 2-way connector located near the base of the steering column and install the CPA. Install the instrument panel access cover.

20.3.

Connect the frontal air bags yellow 4-way connector, install the CPA and clip the connector to the metal rail. Install the passenger side instrument panel access cover.

20.4.

Install the SDM fuse and install the driver's side instrument panel access cover.

20.5.

Do NOT verify SIR system operation at this time.

Important: If you need help with the Reprogramming of the Body Control Module (BCM) in the next steps, contact the Techline Customer Support Center on 1-800-828-6860 (French: 1-800-503-3222) before proceeding to Step 21.

21. Reprogram the BCM to accept the new SDM part number using the following procedure.

Important: In order to perform the reprogramming, your Techline terminal must be updated with CD #17 which you should have received in September, 2000. Before proceeding, verify that your Techline terminal has the required update. All CD's received in the future will continue to have this required software.

22. Connect your Tech 2 to the vehicle and select "Service Programming". Follow the on-screen instructions and "Request Information".

Important: The module being reprogrammed in the next step is the Body Control Module (BCM).

23. Take the Tech 2 to the Techline terminal and select "TIS 2000". Select "Service Programming" and follow the on-screen instructions for programming the BCM.
24. Return to the vehicle and reconnect the Tech 2.
25. Select "Programming" followed by "Program the BCM" and follow the on-screen instructions.
26. After the programming is completed, exit to the main menu on the Tech 2 and disconnect it from the vehicle.
27. Turn the ignition switch to the OFF position and then turn it to the ON position.
28. Verify that the AIR BAG warning lamp flashes seven (7) times and goes out.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: