GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2004 🢒 GTO 🢒 DTC 🢒 DTC 21 or 22

Circuit Description

The steering wheel module deployment loop consists of a inflatable restraint steering wheel module, an inflatable restraint steering wheel module coil, the steering wheel module high and steering wheel module low circuits. A shorting bar used in the inflatable restraint steering wheel module and the inflatable restraint steering wheel module coil connectors which will short together the steering wheel module high and steering wheel module low circuits when the connector is disconnected, this will help to prevent unwanted deployment of the inflator module during servicing. During a frontal crash of sufficient force the SDM will allow current to flow through the deployment loop in order to deploy the inflatable restraint steering wheel module. The SDM performs continuous diagnostic tests on the deployment loops to check for proper circuit continuity and for shorts to ground or voltage. If a malfunction is detected, a DTC will be stored.

Conditions for Running the DTC

Ignition Voltage is within the normal operating voltage range.

Conditions for Setting the DTC
    • DTC 21 will set when the SDM detects a high resistance condition in the steering wheel module deployment loop.
    • DTC 22 will set when the SDM detects a low resistance condition in the steering wheel module deployment loop.

Action Taken When the DTC Sets

The SDM commands the AIR BAG indicator ON.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.

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 the reappearance of the malfunction.

The following are possible causes of the malfunction:

    • An open or high resistance in the steering wheel module high or the steering wheel module low circuits
    • A short between the steering wheel module high and the steering wheel module low circuits
    • A malfunctioning inflatable restraint steering wheel module
    • A malfunctioning inflatable restraint steering wheel module coil
    • An internal SDM malfunction

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

Test Description

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

  1. Tests to see if the malfunction is caused by the inflatable restraint steering wheel module.

    2.

  2. Tests to see if the malfunction is caused by the inflatable restraint steering wheel module coil.

    3.

  3. Tests to see if the malfunction is caused by the inflatable restraint steering wheel module coil.

    4.

  4. If DTC 21 is present, test the steering wheel module high and the steering wheel module low circuits for an open or high resistance.

    If DTC 22 is present, test for a short between the steering wheel module high and the steering Wheel Module - Low circuits.

Step

Action

Yes

No

Schematic Reference: SIR Schematics

Connector End View Reference: SIR Connector End Views

1

Did you perform aDiagnostic System Check - SIR?

Go to Step 2

Go to Diagnostic System Check - SIR

2

Is DTC 21 or 22 set as a current DTC?

Go to Step 3

Go to Diagnostic Aids

3
  1. Turn OFF the ignition.
  2. Remove the steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
  3. Inspect both the component and harness sides of the steering wheel module connectors for damage or corrosion that may cause the malfunction. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Does the connector exhibit any signs of damage or corrosion?

Go to Step 4

Go to Step 5

4
    • If the component side of the steering wheel module connector is damaged, the steering wheel module must be replaced. Refer to Inflatable Restraint Steering Wheel Module Replacement .
    • If the harness side of the steering wheel module connector is damaged, the steering wheel module coil must be replaced. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .

Did you complete the replacement?

Go to Step 15

--

5

  1. Install EL-46867 SIR Driver/Passenger Load Tool to the steering wheel module harness connector.
  2. Connect the battery. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  3. Use the scan tool in order to Clear the DTCs.
  4. With the scan tool request the DTC display.

Does the scan tool indicate that DTC 21 or 22 is current?

Go to Step 6

Go to Step 12

6

Is DTC 21 set as a current DTC?

Go to Step 8

Go to Step 7

7

Is DTC 22 set as a current DTC?

Go to Step 9

--

8

  1. Disconnect the lower steering wheel module coil connector.
  2. Connect a suitable jumper wire between the steering wheel module high and the steering wheel module low circuits on the harness side of the steering wheel module coil connector.
  3. Use the scan tool in order to Clear the DTCs.
  4. With the scan tool, request the SIR DTC display.

Does the scan tool indicate that DTC 21 is current?

Go to Step 10

Go to Step 13

9

  1. Disconnect the lower steering wheel module coil connector.
  2. Use the scan tool in order to Clear the DTCs.
  3. With the scan tool, request the SIR DTC display.

Does the scan tool indicate that DTC 22 is current?

Go to Step 10

Go to Step 13

10
  1. Turn OFF the ignition.
  2. Disconnect the SDM connector.
  3. Inspect the SDM connector for damage or corrosion that may cause a malfunction between the steering wheel module high and/or the steering wheel module low circuits. 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 15

Go to Step 11

11

    • If DTC 21 is present, test the steering wheel module high and the steering wheel module low circuits for an open or high resistance.
    • If DTC 22 is present, test for a short between the steering wheel module high and the steering wheel module low circuits.
    • All the above conditions refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 14

12
  1. Turn OFF the ignition.
  2. Replace the steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .

Did you complete the replacement?

Go to Step 15

--

13

  1. Turn OFF the ignition.
  2. Replace the steering wheel module coil. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .

Did you complete the replacement?

Go to Step 15

--

14

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

Did you complete the replacement?

Go to Step 15

--

15
  1. Reconnect all SIR components.
  2. Verify that all components, connectors and CPAs are properly mounted.
  3. Use the scan tool in order to Clear the DTCs.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK