GM Service Manual Online
For 1990-2009 cars only

Circuit Description

When the ignition switch is first turned to ON, ignition voltage is applied to the instrument fuse for the indicator lamp and also to the air bag fuse for input terminal A10. If ignition voltage is outside the range of 9 to 16 volts, the AIR BAG indicator will come on and stay on with no DTCs set.

The AIR BAG indicator will stay on if the sensing and diagnostic module (SDM) connector is not securely attached to the SDM. There is a shorting bar in SDM connector which completes the circuit between the indicator lamp circuit and ground. The shorting bar is disengaged when the connector is properly attached. A short ground between the SDM and the indicator lamp could also cause the AIR BAG indicator to stay on.

Step

Action

Values

Yes

No

Schematic Reference: SIR Schematics

Connector End View Reference: Component Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

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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. Inspect the SDM connector and the shorting bar for damage or corrosion.

Did you find and correct the condition?

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Go to Step 7

Go to Step 3

3

Measure the voltage at terminal A10 of the SDM connector. Refer to Circuit Testing and Wiring Repairs.

Does the voltage measure as specified?

9-16 V

Go to Step 4

Go to Step 5

4

Test the air bag indicator control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 7

Go to Step 6

5

Repair the open, high resistance or short to ground in the SDM ignition voltage circuit. Refer to Circuit Testing and Wiring Repairs.

Is the repair complete?

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Go to Step 7

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6

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

Did you complete the replacement?

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Go to Step 7

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7

  1. Reconnect all SIR components.
  2. Verify that all components, connectors and connector position assurances (CPAs) are properly mounted.
  3. Use the scan tool in order to clear the DTCs.
  4. Operate the vehicle in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 2