GM Service Manual Online
For 1990-2009 cars only

Circuit Description

When the ignition switch is turned to ON, the sensing and diagnostic module (SDM) will perform a turn-on test to diagnose critical malfunctions within the SDM itself.

Upon passing this test, ignition and deployment loop voltages are measured to ensure that they are within their normal voltage ranges. The SDM monitors the voltages at the driver low and the passenger low to detect shorts to ground or voltage in the deploy loops.

The SDM inspects the wiring connection to the passenger air bag module by letting the infinitesimal current flow through the internal circuit and verify the resistance. If the voltage is out of range, the SDM is unable to inspect the air bag properly.

Conditions for Setting the DTC

The voltage supplied from the battery is over 16.5 volts.

Step

Action

Values

Yes

No

Caution: Refer to Sensing and Diagnostic Module Voltage after Ignition is Turned Off Caution in the Preface section.

Caution: Refer to Sensing and Diagnostic Module Handling Caution in the Preface section.

 

1

Perform the Diagnostic System Check - SIR.

Did you perform the Diagnostic System Check - SIR?

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Go to Step 2

Go to Diagnostic System Check - SIR

2

Inspect the vehicle charging system. Refer to Charging System Test in Engine Electrical.

Is the charging system OK?

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Go to Step 4

Go to Step 3

3

Repair the charging system.

Did you complete the repair?

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Go to Diagnostic System Check - SIR

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4

  1. Disconnect the negative battery cable.
  2. Replace the sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Did you complete the repair?

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Go to Diagnostic System Check - SIR

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