Air Bag Indicator Circuit Malfunction

Air Bag Indicator Circuit Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

Circuit/System Description

When the ignition is turned ON, the instrument panel cluster (IPC) flashes the AIR BAG indicator seven times. The inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within the SIR system. If no SIR system malfunctions exists, the SDM will request the IPC to turn the air bag indicator OFF after it has flashed 7 times. The AIR BAG indicator is controlled by the SDM via class 2 serial data.

Diagnostic Aids

* If the ignition 1 voltage for the SDM is outside of the normal operating voltage range (9-16 volts), the air bag indicator will continuously illuminate and no DTC will set.
* The loss of serial data communication between the SDM and the IPC will cause the air bag indicator to continuously illuminate. Refer to DTC U1001-U1254 (U1001).

Reference Information
Schematic Reference

SIR Schematics ([1][2]Air Bag Systems)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

SIR System Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Testing

1. Ignition ON, observe the function of the air bag indicator lamp, the indicator lamp will flash 7 times and go OFF.

• If the air bag indicator continuously illuminates, check the serial data signal circuit for a short to ground or an open/high resistance.
• If the air bag indicator continually flashes, program the SDM.

2. Command the air bag lamp ON and OFF with a scan tool, the air bag indicator should turn ON and OFF while changing between the commanded states.

• If the air bag indicator does not illuminate, replace the IPC.

3. If all tests are normal, replace the SDM.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* SIR/SRS Wiring Repairs (SIR/SRS Wiring Repairs)
* Control Module References (Programming and Relearning) for SDM and IPC replacement, setup, and programming