GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Optra 🢒 DTC 🢒 DTC 004

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.

Conditions for Setting the DTC
    • The air bag wiring of the driver high is shorted to battery wiring.
    • The air bag wiring of the driver low is shorted to battery wiring.

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?

Go to Step 2

Go to Diagnostic System Check - SIR

2

Visually inspect the supplemental inflatable restraints (SIR) harness for damage.

Is there any visible damage to the SIR harness?

--

Go to Step 3

Go to Step 4

3
  1. Replace the SIR wiring harness.
  2. Reconnect the negative battery cable.

Did you complete the repair?

--

Go to Diagnostic System Check - SIR

--

4
  1. Remove the driver air bag module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
  2. Place the driver air bag module in a secure position with the decorative surface facing upward.
  3. Disconnect the electrical connector at the sensing and diagnostic module (SDM).

    4. The shorting bar at the disconnected SDM connector will create a complete circuit between the wires from the driver air bag module.

  4. Use a multimeter to measure the voltage at one of the terminals on the wiring harness connector for the driver air bag module.

Does the voltage measure greater than the specified value?

0 V

Go to Step 7

Go to Step 5

5
  1. Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  2. Reconnect the negative battery cable.
  3. Set the scan tool for CODE ERASE.
  4. Perform the Diagnostic System Check - SIR.

Is DTC 004 still shown as a current fault?

--

Go to Step 6

System OK

6
  1. Replace the driver air bag module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
  2. Reconnect the negative battery cable.

Did you complete the repair?

--

Go to Diagnostic System Check - SIR

--

7
  1. Disconnect the clock spring wiring harness at the lower steering column.

    2. The shorting bar at the disconnected SDM connector will create a complete circuit between the wires from the clock spring.

  2. Using a multimeter, measure the voltage at one of the terminals on the SDM side of the clock spring connector.

Is the voltage equal to the specified value?

0 V

Go to Step 8

Go to Step 3

8
  1. Replace the clock spring. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .
  2. Reconnect the negative battery cable.

Did you complete the repair?

--

Go to Diagnostic System Check - SIR

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