GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The ignition switch supplies Ignition 1 voltage to the inflatable restraint sensing and diagnostic module (SDM) at terminal A1 using the SIR Fuse. The ignition switch also supplies voltage to the instrument panel cluster (IP). The AIR BAG warning indicator is controlled by the SDM via Class 2 serial data. When the ignition switch is first turned ON, the SDM responds by performing tests on the SIR system and then commanding the AIR BAG warning indicator OFF after it has flashed seven times.

Diagnostic Aids

If battery voltage is outside of the normal operating voltage range, 9-16 volts, the AIR BAG warning lamp will come ON solid with no DTCs set.

Step

Action

Value(s)

Yes

No

Schematic Reference: SIR Schematics

1

Did you perform A Diagnostic System Check - SIR?

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Go to Step 2

Go to Diagnostic System Check - SIR

2

  1. Turn ON the ignition, with the engine OFF.
  2. Using a scan tool establish communication with the SDM.
  3. Use the scan tool to request the SIR data list display.
  4. With a scan tool, observe the ignition voltage parameter in the SIR data list.

Does the scan tool indicate that the ignition voltage is within the specified range?

9-16 V

Go to Step 3

Go to Charging System Test in Engine Electrical

3

  1. Turn OFF the ignition.
  2. Remove the scan tool.
  3. Turn ON the ignition, with the engine OFF.
  4. All indicators will turn ON, find the AIR BAG indicator.
  5. The AIR BAG indicator should illuminate and flash seven times before turning OFF.

Does AIR BAG Warning Indicator turn ON?

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Go to Step 4

Go to Step 5

4

Replace the inflatable restraint sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Did you complete the replacement?

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Go to Diagnostic System Check - SIR

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5

The AIR BAG warning lamp is not serviceable separately. The instrument panel cluster (IPC) must be service as a complete unit. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console.

Did you complete the repair?

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Go to Diagnostic System Check - SIR

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