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.

In case of the 1st stage air bag inflation by a vehicle collision, the SDM maintains the warning lamp ON and all the air bag systems including the SDM, air bag module, and wiring should be replaced.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1650 Frontal Stage 1 Deployment Commanded

Conditions for Running the DTC

Ignition voltage is within the normal operating voltage range.

Conditions for Setting the DTC

The history of the 1st stage air bag inflation or the belt pretensioner explosion is in the SDM.

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.

Step

Action

Values

Yes

No

Caution: Refer to Sensing and Diagnostic Module Handling Caution in the Preface section.

Caution: Refer to Sensing and Diagnostic Module Voltage after Ignition is Turned Off Caution in the Preface section.

Schematic Reference: SIR Schematics

Connector End View Reference: SIR Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Confirm the ignition switch is OFF.
  2. Wait for 1 minute for the sensing and diagnostic module (SDM) charger to be discharged.

Has the SDM discharged?

--

Go to Step 3

--

3

Visually inspect any damage for the air bag wiring.

Is the air bag wiring damaged?

--

Go to Step 5

Go to Step 4

4

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

Is the replacement complete?

--

Go to Step 6

--

5

Replace the air bag wiring.

Is the replacement complete?

--

Go to Step 6

--

6

  1. Reconnect all SIR system components.
  2. Verify that all components, connectors, and connector position assurances (CPAs) are properly mounted.
  3. Use the scan tool to clear the DTCs.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the text.

Does the DTC reset?

--

Go to Step 2

System OK