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 SDM itself.

These 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 battery by letting the perpetual 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 system properly.

Conditions for Setting the DTC

The voltage supplied from the battery is over 16.5 volts.

Step

Action

Yes

No

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

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

 

1

Inspect the vehicle's charging system including the alternator.

Is the charging system OK?

Go to Step 3

Go to Step 2

2

Repair the charging system.

Is the repair complete?

Go to Step 1

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3

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

Is the repair complete?

Go to Diagnostic System Check - SIR

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