GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The ignition switch supplies battery voltage to the AIR BAG indicator using the AM2 fuse. The AIR BAG indicator is connected to the AIR BAG indicator control circuit of the sensing and diagnostic module (SDM). When the ignition switch is first turned to the ON position, the SDM responds by illuminating the AIR BAG indicator for approximately 6 seconds while performing diagnostic tests on the SIR system.

Diagnostic Aids

Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and the connectors may result in a misdiagnosis, causing a part replacement with the reappearance of the malfunction.

The following are possible causes of the malfunction:

    • A short to ground in the diagnostic request circuit
    • An internal SDM malfunction

If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections .

Step

Action

Yes

No

Schematic Reference: SIR Schematics

Connector End View Reference: SIR Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn OFF the ignition.
  2. Disconnect the sensing and diagnostic module (SDM) connector.
  3. Test the diagnostic request circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 4

Go to Step 3

3

Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Did you complete the replacement?

Go to Step 4

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4

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2