GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The inflatable restraint sensing and diagnostic module (SDM) contains a sensing device that converts vehicle velocity changes into an electrical signal. The SDM compares this electrical signal to a value stored in memory. When the generated signal exceeds the stored value, the SDM performs additional signal processing and compares the generated signals to values stored in memory. When two of the generated signals exceed the stored values, the SDM will cause current to flow through the inflator modules, deploying the air bags, and causing diagnostic trouble code (DTC) B0051 to set.

Conditions for Running the DTC

Ignition 1 Voltage is within the normal operating voltage range.

Conditions for Setting the DTC

The SDM detects a frontal crash of sufficient force to warrant deployment of the frontal air bags.

Action Taken When the DTC Sets

    • The SDM commands the AIR BAG indicator ON.
    • The SDM records crash data.

Conditions for Clearing the DTC

DTC B0051 is a latched code which cannot be cleared. Replace the SDM after following the instructions in the diagnostic table.

Step

Action

Yes

No

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. Inspect the vehicle for signs of inflator module deployment.

Does the vehicle show any signs of inflator module deployment?

Go to Step 5

Go to Step 3

3

Inspect the front of the vehicle and undercarriage for signs of impact/collision.

Does the vehicle show any signs of impact/collision?

Go to Step 5

Go to Step 4

4

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

Did you complete the replacement?

Go to Step 6

--

5

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With the scan tool request the SIR DTC display.
  4. If a history DTC exists, refer to Diagnostic Aids for that specific DTC and diagnose the problem.
  5. Replace components and perform inspections as required following an accident. Refer to Repairs and Inspections Required After a Collision .

Did you complete the appropriate inspections and necessary repairs?

Go to Step 6

--

6

  1. Use the scan tool in order to clear the DTCs.
  2. 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