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) using the AIR BAG fuse. The ignition switch also supplies battery voltage to the AIR BAG indicator using the IG fuse. The AIR BAG indicator is connected to the AIR BAG indicator output of the SDM. When the ignition switch is first turned to the ON position, the SDM responds by flashing the AIR BAG indicator seven times. If the ignition 1 voltage is outside of the normal operating voltage range (9.0 - 16.0 volts) for more than 25 ms, the AIR BAG indicator will turn ON with no DTCs set.

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 a reappearance of the malfunction. If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Tests for proper operation of the Air Bag Indicator Control circuitry. With the SDM connector disconnected, the shorting bar connects the Air Bag Indicator Control circuit to ground and should illuminate the indicator.

Step

Action

Yes

No

Schematic Reference: SIR Schematics

1

Did you perform A Diagnostic System Check - SIR?

Go to Step 2

Go to Diagnostic System Check - SIR

2

Do any of the other instrument cluster indicators or gages function?

Go to Step 3

Go to Gages Inoperative - All in Instrument Panel, Gages and Console

3

  1. Turn OFF the ignition.
  2. Disconnect the SDM connector.
  3. Turn ON the ignition, with the engine OFF.

Does the AIR BAG indicator come ON?

Go to Step 5

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Inspect the SDM connector for the following conditions:
  3. • Corrosion
    • Damaged terminals
    • Poor connections/terminal tension

Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 7

Go to Step 6

5

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

Did you complete the replacement?

Go to Step 7

--

6

Repair the open or high resistance in the Air Bag Indicator Control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 7

--

7

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2