GM Service Manual Online
For 1990-2009 cars only

Circuit Description

When the ignition is turned ON, the inflatable restraint sensing and diagnostic module (SDM) flashes the AIR BAG indicator seven times. The SDM performs diagnostic tests on the SIR system and then turns the AIR BAG indicator OFF if no SIR malfunctions exist. If the ignition 1 voltage is outside of the normal operating range (9-16 volts), the SDM will turn the AIR BAG indicator ON with no DTCs present.

Diagnostic Aids

The AIR BAG indicator will turn ON if the SDM connector is damaged or not properly connected to the SDM. The AIR BAG indicator will also turn ON if the shorting bar that is located within the SDM connector is damaged. In order to disable the shorting bar from the AIR BAG indicator control circuit and the SDM ground circuit within the SDM connector, the following conditions must be met:

    • The SDM connector must be properly connected to the SDM.
    • The connector position assurance (CPA) must be properly installed to the SDM connector.

Test Description

The numbers below refer to the step numbers on the diagnostic table:

  1. Tests to see if the ignition 1 voltage is more than 9 V

  2. Tests to see if the ignition 1 voltage is more than 16 V

  3. Tests to see if the SDM connector retainer assembly is damaged or corroded

  4. Tests to see if the SDM connector is damaged or corroded

  5. Tests to see if the SDM connector properly seats into the SDM

  6. Tests to see if there is a short to ground in the AIR BAG indicator control circuit

  7. Tests to see if the SDM connector retainer assembly is damaged or corroded

  8. Tests to see if the SDM connector is damaged or corroded

  9. Tests to see if there is an open, high resistance, or a short to ground in the ignition 1 voltage feed circuit

  10. Tests to see if there is an open or a high resistance in the SDM ground circuit

Step

Action

Value(s)

Yes

No

Schematic Reference: SIR Schematics

1

Did you perform the Diagnostic System Check - SIR?

--

Go to Step 2

Go to Diagnostic System Check - SIR

2

  1. Turn OFF the ignition.
  2. Note the AIR BAG indicator while turning ON the ignition.

Does the AIR BAG indicator remain ON at all times?

--

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

3

  1. Install a scan tool.
  2. With a scan tool, observe the SIR data list display.

Does the scan tool indicate that the ignition voltage is greater than the specified value?

9 V

Go to Step 4

Go to Step 12

4

Does the scan tool indicate that the ignition voltage is greater than the specified value?

16 V

Go to Diagnostic System Check - Engine Electrical in Engine Electrical

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Disconnect the SDM connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Use a small flat head screwdriver to remove the retainer assembly from the SDM connector by gently lifting the locking tabs on the ends of the retainer assembly.
  4. Inspect the retainer assembly and shorting bar for damage or corrosion.

Does the retainer assembly exhibit signs of damage or corrosion?

--

Go to Step 6

Go to Step 7

6

  1. Replace the retainer assembly.
  2. Follow the instructions in the GM Kit 12167318 in order to properly install a new retainer assembly.

Did you complete the replacement?

--

Go to Step 18

--

7

Inspect the SDM connector for damage or corrosion. 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 18

Go to Step 8

8

  1. Follow the instructions in the GM Kit 12167318 in order to properly reinstall the retainer assemble.
  2. Important:  It is very important to properly inspect the SDM terminals and the shorting bar lifting tab in order to avoid misdiagnosis.

  3. Inspect the SDM terminals for damage or corrosion.
  4. Also, inspect the shorting bar lifting tab to ensure that it is not damaged.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 9

9

  1. Connect the SDM connector to the SDM.
  2. Install the CPA.

Does the SDM connector properly connect to the SDM with the CPA properly installed?

--

Go to Step 11

Go to Step 10

10

Replace the SDM connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the replacement?

--

Go to Step 18

--

11

  1. Turn OFF the ignition.
  2. Disconnect the instrument panel cluster (IPC). Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.
  3. Test the AIR BAG indicator control circuit for a short to ground.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 17

12

  1. Turn OFF the ignition.
  2. Disconnect the SDM connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Use a small flat head screwdriver to remove the retainer assembly from the SDM connector by gently lifting the locking tabs on the ends of the retainer assembly.
  4. Inspect the retainer assembly and shorting bar for damage or corrosion.

Does the retainer assembly exhibit signs of damage or corrosion?

--

Go to Step 13

Go to Step 14

13

  1. Replace the retainer assembly.
  2. Follow the instructions in the GM Kit 12167318 in order to properly install a new retainer assembly.

Did you complete the replacement?

--

Go to Step 18

--

14

Inspect the SDM connector for damage or corrosion. 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 18

Go to Step 15

15

Test the ignition 1 voltage feed circuit for an open, high resistance, or short to ground.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 16

16

Test the SDM ground circuit for an open or a high resistance.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 17

17

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

Did you complete the replacement?

--

Go to Step 18

--

18

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3