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 the SDM itself.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1000 ECU Malfunction

Conditions for Running the DTC

Ignition voltage is within the normal operating voltage range.

Conditions for Setting the DTC

The SDM does not pass internal tests.

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

The wiring harness of the SDM should be inspected before replacing the SDM.

Step

Action

Yes

No

Warning: Refer to SIR Warning in the Preface section.

Schematic Reference: SIR Schematics

Connector End View Reference: Component Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn the ignition OFF.
  2. Wait 1 minute for the SDM capacitor to discharge.
  3. Visually inspect the supplemental inflatable restraint (SIR) wiring harness.

Is there any visible damage to the SIR harness?

Go to Step 4

Go to Step 3

3

Replace the sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement.

Did you complete the replacement?

Go to Step 5

--

4

Repair or replace the SIR wiring harness.

Did you complete the replacement?

Go to Step 5

--

5

  1. Reconnect all SIR components.
  2. Verify that all components, connectors and connector position assurances (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