When the ignition is first turned ON, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. The SDM is hard-wired to the body control module (BCM) through the deployment commanded output (DCO) circuit. During CONTINUOUS MONITORING, the SDM sends fixed frequency pulses to the BCM. In the event of a collision involving inflator module or seat belt pretensioner deployment, the SDM sends higher frequency pulses to the BCM, which in turn sends a Class 2 message to the ONSTAR module. Upon receiving the Class 2 message, the ONSTAR module transmits a DCO signal to the service center via the vehicle's cellular telephone.
Ignition 1 voltage is within the normal operating voltage range.
The measured leakage current to voltage or the resistance of the DCO circuit are above a specified value caused by a short to voltage, open or a high resistance in the DCO circuit.
The SDM turns the AIR BAG indicator ON.
• | The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used. |
• | A history DTC will clear once 255 malfunction free ignition cycles have occurred. |
Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and the connectors may result in misdiagnosis, causing a part replacement with reappearance of the malfunction.
The following are possible causes of the malfunction:
• | A short to voltage, open or high resistance in the DCO circuit |
• | The SDM connector |
• | The BCM connector C1 |
• | An internal SDM malfunction |
• | An internal BCM malfunction |
If an intermittent condition exists, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Tests to see if the SDM connector is damaged or corroded.
Tests to see if the SDM terminals are damaged or corroded.
Tests to see if the BCM connector C1 is damaged or corroded.
Tests to see if the BCM terminals are damaged or corroded.
Tests to see if there is a short to voltage, open or a high resistance in the DCO circuit.
Tests to see if the communication status and the units displayed for the DCO circuit are correct.
Step | Action | Yes | No |
---|---|---|---|
Schematic Reference: SIR Schematics | |||
1 | Did you perform A Diagnostic System Check - SIR? | Go to Step 2 | |
Did you find and correct the condition? | Go to Step 10 | Go to Step 3 | |
Inspect the SDM terminals for corrosion or damage that may cause the malfunction. Do the SDM terminals exhibit any sign of damage or corrosion? | Go to Step 9 | Go to Step 4 | |
Did you find and correct the condition? | Go to Step 10 | Go to Step 5 | |
Inspect the BCM terminals for corrosion or damage that may cause the malfunction. Do the BCM terminals exhibit any sign of damage or corrosion? | Go to Step 8 | Go to Step 6 | |
Test the DCO circuit for a short to voltage, open or a high resistance. Did you find and correct the condition? | Go to Step 10 | Go to Step 7 | |
Does the scan tool indicate that the ONSTAR test flag displays SET and the ONSTAR signal displays OK? | Go to Step 9 | Go to Step 8 | |
8 | Replace the BCM. Refer to Body Control Module Replacement in Body Control System. Did you complete the replacement? | Go to Step 10 | -- |
9 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Did you complete the replacement? | Go to Step 10 | -- |
10 |
Does the DTC rest? | Go to Step 2 | System OK |