Air Bag Indicator Illuminates Intermittently, IPC and Sensing and Diagnostic Module (SDM) DTC U1000 Set (Replace Front End Sensor Assembly and/or Sensing Diagnostic Module)

Some customers may comment that after starting the vehicle, the Air Bag Readiness Light/Indicator on the instrument panel cluster (IPC) flashes for a few seconds (6-10 times) and then remains illuminated until the next ignition cycle.

Technicians may find a SDM and IPC U1000 DTC and an OnStar® System U1088 DTC set in history.

This condition may be due to a unique Class 2 communication software issue within the Sensing and Diagnostic Module (SDM).

1. Use the scan tool to:

•	Perform the standard SIR diagnostic system check in order to verify the condition. Refer to Diagnostic System Check-SIR in the SIR sub-section of the appropriate Service Manual.

•	Obtain the part number of the existing SDM.

2. On CTS models only, obtain the part number of the existing inflatable restraint front end sensor.
3. If the scan tool displays DTCs U1000 and U1088 and the existing SDM part number is NOT listed in the Parts Information table in this bulletin, go to Step 5 for DeVille and Step 6 for CTS.
4. If the scan tool does NOT display DTCs U1000 and U1088, perform the diagnostic procedure as indicated in the Diagnostic System Check-SIR in the Service Manual.
5. For DeVille models, replace the SDM only. Refer to the Inflatable Restraint Sensing and Diagnostic Module Replacement procedures in the SIR sub-section of the Service Manual.
6. For CTS models:

•	Replace the SDM. Refer to the Inflatable Restraint Sensing and Diagnostic Module Replacement procedures in the SIR sub-section of the Service Manual.

•	If the existing front end sensor is NOT P/N 25744736, replace it with P/N 25744736. Refer to the Inflatable Restraint Front End Sensor Replacement procedures in the SIR sub-section of the Service Manual.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: